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Document and Entity Information Document - USD ($)	12 Months Ended
Document and Entity Information Document - USD ($)	Dec. 31, 2012	Feb. 01, 2013	Jun. 30, 2012
Document Information [Line Items]
Entity Registrant Name	ALLETE INC
Entity Central Index Key	0000066756
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,591,836,880
Entity Common Stock, Shares Outstanding		39,468,463
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2012

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2012	Dec. 31, 2011
Current Assets
Cash and Cash Equivalents	$ 80.8	$ 101.1
Accounts Receivable (Less Allowance of $1.0 and $0.9)	89.0	79.7
Inventories	69.8	69.1
Prepayments and Other	33.6	27.1
Total Current Assets	273.2	277.0
Property, Plant and Equipment - Net	2,347.6	1,982.7
Regulatory Assets	340.3	345.9
Investment in ATC	107.3	98.9
Other Investments	143.5	132.3
Other Non-Current Assets	41.5	39.2
Total Assets	3,253.4	2,876.0
Current Liabilities
Accounts Payable	90.5	71.8
Accrued Taxes	30.2	26.4
Accrued Interest	15.6	12.8
Long-Term Debt Due Within One Year	84.5	5.4
Notes Payable	0.0	1.1
Other	62.6	45.6
Total Current Liabilities	283.4	163.1
Long-Term Debt	933.6	857.9
Deferred Income Taxes	423.8	373.6
Regulatory Liabilities	60.1	43.5
Defined Benefit Pension and Other Postretirement Benefit Plans	228.2	253.5
Other Non-Current Liabilities	123.3	105.1
Total Liabilities	2,052.4	1,796.7
Commitments and Contingencies (Note 11)
Equity
Common Stock Without Par Value, 80.0 Shares Authorized, 39.4 and 37.5 Shares Outstanding	784.7	705.6
Unearned ESOP Shares	(21.3)	(29.0)
Accumulated Other Comprehensive Loss	(22.0)	(28.9)
Retained Earnings	459.6	431.6
Total Equity	1,201.0	1,079.3
Total Liabilities and Equity	$ 3,253.4	$ 2,876.0

Consolidated Balance Sheet Parentheticals - USD ($) $ / shares in Thousands, shares in Millions, $ in Millions	Dec. 31, 2012	Dec. 31, 2011
Accounts Receivable [Abstract]
Accounts Receivable, Allowance	$ 1.0	$ 0.9
Common Stock [Abstract]
Common Stock, Par Value	$ 0	$ 0
Common Stock, Shares Authorized	80.0	80.0
Common Stock, Shares Outstanding	39.4	37.5

Consilidated Statement of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Revenue	$ 961.2	$ 928.2	$ 907.0
Operating Expenses
Fuel and Purchased Power	308.7	306.6	325.1
Operating and Maintenance	397.1	381.2	365.6
Depreciation	100.2	90.4	80.5
Total Operating Expenses	806.0	778.2	771.2
Operating Income	155.2	150.0	135.8
Other Income (Expense)
Interest Expense	(45.5)	(43.6)	(39.2)
Equity Earnings in ATC	19.4	18.4	17.9
Other	6.0	4.4	4.6
Total Other Expense	(20.1)	(20.8)	(16.7)
Income Before Non-Controlling Interest and Income Taxes	135.1	129.2	119.1
Income Tax Expense	38.0	35.6	44.3
Net Income	97.1	93.6	74.8
Less: Non-Controlling Interest in Subsidiaries	0.0	(0.2)	(0.5)
Net Income Attributable to ALLETE	$ 97.1	$ 93.8	$ 75.3
Average Shares of Common Stock
Basic (in shares)	37.6	35.3	34.2
Diluted (in shares)	37.6	35.4	34.3
Basic Earnings Per Share of Common Stock	$ 2.59	$ 2.66	$ 2.20
Diluted Earnings Per Share of Common Stock	2.58	2.65	2.19
Dividends Per Share of Common Stock	$ 1.84	$ 1.78	$ 1.76

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Income	$ 97.1	$ 93.6	$ 74.8
Other Comprehensive Income (Loss) [Abstract]
Unrealized Gain (Loss) on Securities - Net of Income Taxes of $0.8, $(0.1) and $0.6	1.2	(0.3)	0.8
Unrealized Loss on Derivatives - Net of Income Taxes of $(0.1), $(0.2) and $-	(0.2)	(0.3)	0.0
Defined Benefit Pension and Other Postretirement Benefit Plans - Net of Income Taxes of $3.9, $(3.6), and $-	5.9	(5.1)	0.0
Total Other Comprehensive Income (Loss)	6.9	(5.7)	0.8
Total Comprehensive Income	104.0	87.9	75.6
Less: Non-Controlling Interest in Subsidiaries	0.0	(0.2)	(0.5)
Comprehensive Income Attributable to ALLETE	$ 104.0	$ 88.1	$ 76.1

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

Net of tax amount, before reclassification adjustments, of the change in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Also includes an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

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+ Details

- Definition

Net of tax amount of unrealized holding gain (loss) before reclassification adjustments and transfers on available-for-sale securities.

+ References

+ Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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+ Details

Consolidated Statement of Comprehensive Income Parentheticals - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statement of Comprehensive Income Parentheticals [Abstract]
Unrealized Gain (Loss) on Securities, Taxes	$ 0.8	$ (0.1)	$ 0.6
Unrealized Loss on Derivatives, Taxes	(0.1)	(0.2)	0.0
Defined Benefit Pension and Other Postretirement Benefit Plans, Taxes	$ 3.9	$ (3.6)	$ 0.0

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Activities
Net Income	$ 97.1	$ 93.6	$ 74.8
Allowance for Funds Used During Construction - Equity	(5.1)	(2.5)	(4.2)
Income from Equity Investments, Net of Dividends	(3.7)	(3.2)	(3.1)
Gain on Real Estate Foreclosure	0.0	(0.5)	(0.7)
Loss (Gain) on Sale of Assets	0.2	(0.9)	0.0
Loss on Impairment of Assets	0.0	1.7	0.0
Depreciation Expense	100.2	90.4	80.5
Amortization of Debt Issuance Costs	1.0	0.9	0.9
Deferred Income Tax Expense	37.5	35.8	66.0
Share-Based Compensation Expense	2.1	1.6	2.2
ESOP Compensation Expense	7.7	7.4	7.1
Defined Benefit Pension and Other Postretirement Benefit Expense	27.5	23.6	18.0
Bad Debt Expense	1.0	1.2	1.1
Changes in Operating Assets and Liabilities
Accounts Receivable	(10.1)	18.6	17.9
Inventories	(0.7)	(9.1)	(3.0)
Prepayments and Other	(6.5)	1.5	(4.3)
Accounts Payable	(1.5)	(9.5)	5.8
Other Current Liabilities	21.8	15.4	5.2
Cash Contributions to Defined Benefit Pension and Other Postretirement Plans	(8.8)	(24.7)	(39.3)
Changes in Regulatory and Other Non-Current Assets	(20.9)	(7.5)	4.2
Changes in Regulatory and Other Non-Current Liabilities	0.8	7.9	(0.4)
Cash from Operating Activities	239.6	241.7	228.7
Investing Activities
Proceeds from Sale of Available-for-sale Securities	1.5	7.8	0.6
Payments for Purchase of Available-for-sale Securities	(1.8)	(2.3)	(2.3)
Investment in ATC	(4.7)	(2.0)	(1.6)
Changes to Other Investments	(9.6)	(7.4)	1.3
Additions to Property, Plant and Equipment	(405.8)	(239.2)	(248.9)
Proceeds from Sale of Assets	0.3	2.2	0.0
Cash for Investing Activities	(420.1)	(240.9)	(250.9)
Financing Activities
Proceeds from Issuance of Common Stock	77.0	39.1	20.5
Proceeds from Issuance of Long-Term Debt	180.6	81.4	155.0
Changes in Notes Payable	(1.1)	0.1	(0.9)
Reductions of Long-Term Debt	(25.9)	(3.1)	(71.0)
Debt Issuance Costs	(1.3)	0.0	(1.4)
Dividends on Common Stock	(69.1)	(62.1)	(60.8)
Cash from Financing Activities	160.2	55.4	41.4
Change in Cash and Cash Equivalents	(20.3)	56.2	19.2
Cash and Cash Equivalents at Beginning of Period	101.1	44.9	25.7
Cash and Cash Equivalents at End of Period	$ 80.8	$ 101.1	$ 44.9

Consolidated Statement of Shareholders' Equity - USD ($) $ in Millions	Total	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Unearned ESOP Shares	Common Stock
Balance at Dec. 31, 2009	$ 929.5	$ 385.4	$ (24.0)	$ (45.3)	$ 613.4
Comprehensive Income
Net Income	74.8	74.8
Other Comprehensive Income - Net of Tax
Unrealized Gain (Loss) on Securities - Net	0.8		0.8
Unrealized Loss on Derivatives - Net	0.0
Defined Benefit Pension and Other Postretirement Plans - Net	0.0
Total Comprehensive Income	75.6
Non-Controlling Interest in Subsidiaries	0.5	0.5
Comprehensive Income Attributable to ALLETE	76.1
Common Stock Issued - Net	22.7				22.7
Dividends Declared	(60.8)	(60.8)
ESOP Shares Earned	8.5			8.5
Balance at Dec. 31, 2010	976.0	399.9	(23.2)	(36.8)	636.1
Comprehensive Income
Net Income	93.6	93.6
Other Comprehensive Income - Net of Tax
Unrealized Gain (Loss) on Securities - Net	(0.3)		(0.3)
Unrealized Loss on Derivatives - Net	(0.3)		(0.3)
Defined Benefit Pension and Other Postretirement Plans - Net	(5.1)		(5.1)
Total Comprehensive Income	87.9
Non-Controlling Interest in Subsidiaries	0.2	0.2
Comprehensive Income Attributable to ALLETE	88.1
Common Stock Issued - Net	69.5				69.5
Dividends Declared	(62.1)	(62.1)
ESOP Shares Earned	7.8			7.8
Balance at Dec. 31, 2011	1,079.3	431.6	(28.9)	(29.0)	705.6
Comprehensive Income
Net Income	97.1	97.1
Other Comprehensive Income - Net of Tax
Unrealized Gain (Loss) on Securities - Net	1.2		1.2
Unrealized Loss on Derivatives - Net	(0.2)		(0.2)
Defined Benefit Pension and Other Postretirement Plans - Net	5.9		5.9
Total Comprehensive Income	104.0
Non-Controlling Interest in Subsidiaries	0.0
Comprehensive Income Attributable to ALLETE	104.0
Common Stock Issued - Net	79.1				79.1
Dividends Declared	(69.1)	(69.1)
ESOP Shares Earned	7.7			7.7
Balance at Dec. 31, 2012	$ 1,201.0	$ 459.6	$ (22.0)	$ (21.3)	$ 784.7

Operations and Significant Accounting Policies

12 Months Ended

Dec. 31, 2012

Operations and Significant Accounting Policies [Abstract]

Operations and Significant Accounting Policies [Text Block]

OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES

Financial Statement Preparation. References in this report to “we,” “us,” and “our” are to ALLETE and its subsidiaries, collectively. We prepare our financial statements in conformity with accounting principles generally accepted in the United States of America. These principles require management to make informed judgments, best estimates, and assumptions that affect the reported amounts of assets, liabilities, revenue, and expenses. Actual results could differ from those estimates.

Subsequent Events. The Company performed an evaluation of subsequent events for potential recognition and disclosure through the time of the financial statements issuance.

Principles of Consolidation. Our consolidated financial statements include the accounts of ALLETE and all of our majority-owned subsidiary companies. All material intercompany balances and transactions have been eliminated in consolidation.

Business Segments. Our Regulated Operations and Investments and Other segments were determined in accordance with the guidance on segment reporting. Segmentation is based on the manner in which we operate, assess, and allocate resources to the business. We measure performance of our operations through budgeting and monitoring of contributions to consolidated net income by each business segment.

Regulated Operations includes our regulated utilities, Minnesota Power and SWL&P, as well as our investment in ATC, a Wisconsin-based regulated utility that owns and maintains electric transmission assets in parts of Wisconsin, Michigan, Minnesota and Illinois. Minnesota Power provides regulated utility electric service in northeastern Minnesota to approximately 143,000 retail customers. Minnesota Power’s non-affiliated municipal customers consist of 16 municipalities in Minnesota and 1 private utility in Wisconsin. SWL&P is also a private utility in Wisconsin and a customer of Minnesota Power. SWL&P provides regulated electric, natural gas and water service in northwestern Wisconsin to approximately 15,000 electric customers, 12,000 natural gas customers and 10,000 water customers. Our regulated utility operations include retail and wholesale activities under the jurisdiction of state and federal regulatory authorities.

Investments and Other is comprised primarily of BNI Coal, our coal mining operations in North Dakota, ALLETE Properties, our Florida real estate investment, and ALLETE Clean Energy, our business aimed at developing or acquiring capital projects that create energy solutions via wind, solar, biomass, hydro, natural gas/liquids, shale resources, clean coal and other clean energy innovations. This segment also includes other business development and corporate expenditures, a small amount of non-rate base generation, approximately 6,100 acres of land in Minnesota, and earnings on cash and investments.

BNI Coal, a wholly-owned subsidiary, mines and sells lignite coal to two North Dakota mine-mouth generating units, one of which is Square Butte. In 2012, Square Butte supplied 50 percent (227.5 MW) of its output to Minnesota Power under a long-term contract. (See Note 11. Commitments, Guarantees and Contingencies.) Coal sales are recognized when delivered at the cost of production plus a specified profit per ton of coal delivered.

ALLETE Properties represents our Florida real estate investment. Our current strategy for the assets is to complete and maintain key entitlements and infrastructure improvements without requiring significant additional investment, sell the portfolio when opportunities arise and reinvest the proceeds in our growth initiatives. ALLETE does not intend to acquire additional Florida real estate.

Full profit recognition is recorded on sales upon closing, provided that cash collections are at least 20 percent of the contract price and the other requirements under the guidance for sales of real estate are met. In certain cases, where there are obligations to perform significant development activities after the date of sale, we recognize profit on a percentage-of-completion basis. From time to time, certain contracts with customers allow us to receive participation revenue from land sales to third parties if various formula-based criteria are achieved.

In certain cases, we pay fees or construct improvements to mitigate offsite traffic impacts. In return, we receive traffic impact fee credits as a result of some of these expenditures. We recognize revenue from the sale of traffic impact fee credits when payment is received.

NOTE 1. OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES (Continued)

Land inventories are accounted for in accordance with the accounting standards for property, plant and equipment, and are included in Other Investments on our Consolidated Balance Sheet. Real estate costs include the cost of land acquired, subsequent development costs and costs of improvements, capitalized development period interest, real estate taxes and payroll costs of certain employees devoted directly to the development effort. These real estate costs incurred are capitalized to the cost of real estate parcels based upon the relative sales value of parcels within each development project in accordance with the accounting standards for real estate. The cost of real estate sold includes the actual costs incurred and the estimate of future completion costs allocated to the real estate sold based upon the relative sales value method. Whenever events or circumstances indicate that the carrying value of the real estate may not be recoverable, impairments are recorded and the related assets are adjusted to their estimated fair value. (See Note 7. Investments.)

ALLETE Clean Energy, a wholly-owned subsidiary of ALLETE, operates independently of Minnesota Power to develop or acquire capital projects aimed at creating energy solutions via wind, solar, biomass, hydro, natural gas/liquids, shale resources, clean coal and other clean energy innovations. ALLETE Clean Energy intends to market to electric utilities, cooperatives, municipalities, independent power marketers and large end-users across North America through long-term contracts or other sale arrangements, and will be subject to applicable state and federal regulatory approvals.

Non-Controlling Interest in Subsidiaries. In August 2011, ALLETE purchased the remaining shares of the ALLETE Properties non-controlling interest at book value for $8.8 million by issuing 0.2 million shares of ALLETE common stock. This was accounted for as an equity transaction, and no gain or loss was recognized in net income or comprehensive income.

Cash and Cash Equivalents. We consider all investments purchased with original maturities of three months or less to be cash equivalents.

Supplemental Statement of Cash Flow Information



Consolidated Statement of Cash Flows
Year Ended December 31	2012		2011		2010
Millions
Cash Paid During the Period for Interest – Net of Amounts Capitalized		$42.7		$43.2		$35.7
Cash Received During the Period for Income Taxes (a)	—		$(11.4)		$(54.2)
Noncash Investing and Financing Activities
Increase in Accounts Payable for Capital Additions to Property, Plant and Equipment		$20.2		$5.9	$7.5
Capitalized Asset Retirement Costs		$17.1		$0.3		$2.8
AFUDC – Equity		$5.1		$2.5		$4.2
ALLETE Common Stock Contributed to the Pension Plan	—		$(20.0)		—


(a)	Due to bonus depreciation provisions in 2009 and 2010 federal legislation, NOLs were generated which resulted in little or no estimated tax payments, and refunds were received from NOL carrybacks against prior years’ taxable income.

Accounts Receivable. Accounts receivable are reported on the balance sheet net of an allowance for doubtful accounts. The allowance is based on our evaluation of the receivable portfolio under current conditions, overall portfolio quality, review of specific problems and such other factors that, in our judgment, deserve recognition in estimating losses.



Accounts Receivable
As of December 31	2012		2011
Millions
Trade Accounts Receivable
Billed		$70.4		$63.7
Unbilled	17.4		15.6
Less: Allowance for Doubtful Accounts	1.0		0.9
Total Trade Accounts Receivable	86.8		78.4
Income Taxes Receivable	2.2		1.3
Total Accounts Receivable - Net		$89.0		$79.7

NOTE 1. OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES (Continued)

Concentration of Credit Risk. Financial instruments that subject us to concentrations of credit risk consist primarily of accounts receivable. Minnesota Power sells electricity to 9 Large Power Customers. Receivables from these customers totaled $11.6 million at December 31, 2012 ($9.3 million at December 31, 2011). Minnesota Power does not obtain collateral to support utility receivables, but monitors the credit standing of major customers. In addition, our taconite-producing Large Power Customers, which are a part of our Regulated Operations segment, are on a weekly billing cycle, which allows us to closely manage collection of amounts due. One of these customers accounted for 12.3 percent of consolidated revenue in 2012 (12.8 percent in 2011; 12.5 percent in 2010). In the third quarter of 2011, one of Minnesota Power’s Large Power Customers, NewPage Corporation (NewPage), filed for Chapter 11 bankruptcy protection. In September 2012, NewPage submitted a motion to the bankruptcy court to approve amended and restated service agreements and payment of the pre-petition amount, which was approved on October 16, 2012. The agreement was subsequently approved by the MPUC in a December 10, 2012 order, which resulted in the pre-petition receivable of $3.2 million being paid as of December 31, 2012. Throughout the bankruptcy proceedings this customer’s operations continued without interruption and we continued to provide electric and steam service to this customer.

Long-Term Finance Receivables. Long-term finance receivables relating to our real estate operations are collateralized by property sold, accrue interest at market-based rates and are net of an allowance for doubtful accounts. We assess delinquent finance receivables by comparing the balance of such receivables to the estimated fair value of the collateralized property. If the fair value of the property is less than the finance receivable, we record a reserve for the difference. We estimate fair value based on recent property tax assessed values or current appraisals. (See Note 7. Investments.)

Available-for-Sale Securities. Available-for-sale securities are recorded at fair value with unrealized gains and losses included in accumulated other comprehensive income (loss), net of tax. Unrealized losses that are other than temporary are recognized in earnings. We use the specific identification method as the basis for determining the cost of securities sold. Our policy is to review available-for-sale securities for other than temporary impairment on a quarterly basis by assessing such factors as the share price trends and the impact of overall market conditions. (See Note 7. Investments.)

Inventories. Inventories are stated at the lower of cost or market. Amounts removed from inventory are recorded on an average cost basis.



Inventories
As of December 31	2012		2011
Millions
Fuel		$28.0		$28.6
Materials and Supplies	41.8		40.5
Total Inventories		$69.8		$69.1

Property, Plant and Equipment. Property, plant and equipment are recorded at original cost and are reported on the balance sheet net of accumulated depreciation. Expenditures for additions, significant replacements, improvements and major plant overhauls are capitalized; maintenance and repair costs are expensed as incurred. Gains or losses on non-rate base property, plant and equipment are recognized when they are retired or otherwise disposed. When regulated utility property, plant and equipment are retired or otherwise disposed, no gain or loss is recognized in accordance with the accounting standards for Regulated Operations. Our Regulated Operations capitalize AFUDC, which includes both an interest and equity component. AFUDC represents the cost of both debt and equity funds used to finance utility plant additions during construction periods. AFUDC amounts capitalized are included in rate base and are recovered from customers as the related property is depreciated. The MPUC has approved cost recovery for several large capital projects recently, at which time the recognition of AFUDC ceases. (See Note 3. Property, Plant and Equipment.)

We believe that long-standing ratemaking practices approved by applicable state and federal regulatory commissions have allowed for the recovery of the remaining basis of retired plant assets. In January 2013 we announced the retirement of Taconite Harbor Unit 3 and conversion of Laskin Energy Center to natural gas in 2015, which is subject to MPUC approval. Accordingly, we do not expect any loss as a result of the retirement of Taconite Harbor Unit 3 or conversion of Laskin Energy Center.

Impairment of Long-Lived Assets. We review our long-lived assets, which include the real estate assets of ALLETE Properties, for indicators of impairment in accordance with the accounting standards for property, plant and equipment on a quarterly basis.

NOTE 1. OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES (Continued)

In accordance with the accounting standards for property, plant and equipment, if indicators of impairment exist, we test our real estate assets for recoverability by comparing the carrying amount of the asset to the undiscounted future net cash flows expected to be generated by the asset. Cash flows are assessed at the lowest level of identifiable cash flows, which may be by each land parcel, combining various parcels into bulk sales, or other combinations thereof. Our consideration of possible impairment for our real estate assets requires us to make estimates of future cash flows on an undiscounted basis. The undiscounted future net cash flows are impacted by trends and factors known to us at the time they are calculated and our expectations related to: management’s best estimate of future sales prices; holding period and timing of sales; method of disposition; and future expenditures necessary to develop and maintain the operations, including community development district assessments, property taxes and normal operation and maintenance costs. These estimates and expectations are specific to each land parcel or various bulk sales, and may vary among each land parcel or bulk sale. If the excess of undiscounted cash flows over the carrying value of a property is small, there is a greater risk of future impairment in the event of such changes and any resulting impairment charges could be material.

Weak market conditions for real estate in Florida have required us to review our land inventories for impairment. Our undiscounted cash flow analysis was estimated using management’s current intent for disposition of each property, which is an estimated selling period of five to ten years based on a December 2011 asset management and disposition plan (“Plan”). The Plan is reviewed annually for adjustment or modification and we have concluded that the estimates and assumptions remain appropriate in 2012. As such, we continue to utilize the Plan when evaluating our land inventory for impairment. Future selling prices have been estimated through management’s best estimate of future sales prices in collaboration and consultation with outside advisors, and based on the best use of the properties over the expected period of sale. The undiscounted cash flow analysis assumes two scenarios: retail land sales followed by project bulk sales over a five year period and retail land sales over a ten year period. Our analysis assumes the most likely case of retail land sales followed by project bulk sales over a five year period; however, under both scenarios, except as noted below, the undiscounted cash flows exceeded carrying values. If our major development projects are sold in one bulk sale or if the properties are sold differently than anticipated in the Plan, the actual results could be materially different from our undiscounted cash flow analysis.

The results of the impairment analysis are particularly dependent on the estimated future sales prices, method of disposition, and holding period for each property. The estimated holding period is based on management’s current intent for the use and disposition of each property, which could be subject to change in future periods if the intentions of the Company as set by management and approved by the Board of Directors were to change.

In the event that projected future undiscounted cash flows are not adequate to recover the carrying value of an asset, impairment is indicated and may require a write down to the asset’s fair value. Fair value is determined based on best available evidence including comparable sales, current appraised values, property tax assessed values, and discounted cash flow analysis. If fair value is less than cost, the carrying value of our investments is reduced and an impairment charge is recorded in the current period. In 2012, impairment analysis’ of estimated future undiscounted cash flows were conducted and indicated that the cash flows were adequate to recover the carrying basis of our land inventory. As a result, there was no impairment recorded for the year ended December 31, 2012. For the year ended December 31, 2011, a $1.7 million impairment charge was recorded.

Derivatives. ALLETE is exposed to certain risks relating to its business operations that can be managed through the use of derivative instruments. ALLETE may enter into derivative instruments to manage interest rate risk related to certain variable-rate borrowings.

Accounting for Stock-Based Compensation. We apply the fair value recognition guidance for share-based payments. Under this guidance, we recognize stock-based compensation expense for all share-based payments granted, net of an estimated forfeiture rate. (See Note 16. Employee Stock and Incentive Plans.)



Prepayments and Other Current Assets
As of December 31	2012		2011
Millions
Deferred Fuel Adjustment Clause		$22.5		$17.5
Other	11.1		9.6
Total Prepayments and Other Current Assets		$33.6		$27.1

NOTE 1. OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES (Continued)



Other Current Liabilities
As of December 31	2012		2011
Millions
Customer Deposits (a)		$28.8		$16.3
Other	33.8		29.3
Total Other Current Liabilities		$62.6		$45.6


(a)	Customer deposits were higher in 2012 primarily due to customer security deposits for capital expenditures relating to a transmission project.



Other Non-Current Liabilities
As of December 31	2012		2011
Millions
Asset Retirement Obligation		$77.9		$57.0
Other	45.4		48.1
Total Other Non-Current Liabilities		$123.3		$105.1

Environmental Liabilities. We review environmental matters for disclosure on a quarterly basis. Accruals for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated, based on current law and existing technologies. These accruals are adjusted periodically as assessment and remediation efforts progress or as additional technical or legal information becomes available. Accruals for environmental liabilities are included in the balance sheet at undiscounted amounts and exclude claims for recoveries from insurance or other third parties. Costs related to environmental contamination treatment and cleanup are charged to operating expense unless recoverable in rates from customers. (See Note 11. Commitments, Guarantees and Contingencies.)

Revenue Recognition. Regulated utility rates are under the jurisdiction of Minnesota, Wisconsin and federal regulatory authorities. Customers are billed on a cycle basis. Revenue is accrued for service provided but not billed. Regulated utility electric rates include adjustment clauses that: (1) bill or credit customers for fuel and purchased energy costs above or below the base levels in rate schedules; (2) bill retail customers for the recovery of conservation improvement program expenditures not collected in base rates; and (3) bill customers for the recovery of certain transmission and renewable energy expenditures. Fuel and purchased power expense is deferred to match the period in which the revenue for fuel and purchased power expense is collected from customers pursuant to the fuel adjustment clause. BNI recognizes revenue when coal is delivered.

Minnesota Power participates in MISO. MISO transactions are accounted for on a net hourly basis in each of the day-ahead and real-time markets. Minnesota Power records net sales in Operating Revenue and net purchases in Fuel and Purchased Power Expense on our Consolidated Statement of Income. The revenues and charges from MISO related to serving retail and municipal electric customers are recorded on a net basis as Fuel and Purchased Power Expense.

Unamortized Discount and Premium on Debt. Discount and premium on debt are deferred and amortized over the terms of the related debt instruments using the straight-line method which approximates the effective interest method.

Income Taxes. ALLETE and its subsidiaries file a consolidated federal income tax return and combined and separate state income tax returns. We account for income taxes using the liability method in accordance with the accounting standards for income taxes. Under the liability method, deferred income tax assets and liabilities are established for all temporary differences in the book and tax basis of assets and liabilities, based upon enacted tax laws and rates applicable to the periods in which the taxes become payable. Due to the effects of regulation on Minnesota Power and SWL&P, certain adjustments made to deferred income taxes are, in turn, recorded as regulatory assets or liabilities. Federal investment tax credits have been recorded as deferred credits and are being amortized to income tax expense over the service lives of the related property. In accordance with the accounting standards for uncertainty in income taxes, we are required to recognize in our financial statements the largest tax benefit of a tax position that is “more-likely-than-not” to be sustained on audit, based solely on the technical merits of the position as of the reporting date. The term “more-likely-than-not” means more than 50 percent likely. (See Note 14. Income Tax Expense.)

NOTE 1. OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES (Continued)

Excise Taxes. We collect excise taxes from our customers levied by government entities. These taxes are stated separately on the billing to the customer and recorded as a liability to be remitted to the government entity. We account for the collection and payment of these taxes on a net basis.

New Accounting Standards.

There are no recently issued accounting standard updates applicable for our adoption in future periods.

Business Segments

12 Months Ended

Dec. 31, 2012

Business Segments [Abstract]

Business Segments [Text Block]

BUSINESS SEGMENTS

Regulated Operations includes our regulated utilities, Minnesota Power and SWL&P, as well as our investment in ATC, a Wisconsin-based regulated utility that owns and maintains electric transmission assets in parts of Wisconsin, Michigan, Minnesota and Illinois. Investments and Other is comprised primarily of BNI Coal, our coal mining operations in North Dakota, ALLETE Properties, our Florida real estate investment, and ALLETE Clean Energy, our business aimed at developing or acquiring capital projects that create energy solutions via wind, solar, biomass, hydro, natural gas/liquids, shale resources, clean coal and other clean energy innovations. This segment also includes other business development and corporate expenditures, a small amount of non-rate base generation, approximately 6,100 acres of land in Minnesota, and earnings on cash and investments. For a description of our reportable business segments, see Item 1. Business.



	Consolidated			Regulated Operations			Investments and Other
Millions
2012
Operating Revenue		$961.2			$874.4			$86.8
Fuel and Purchased Power Expense	308.7			308.7			—
Operating and Maintenance Expense	397.1			310.0			87.1
Depreciation Expense	100.2			93.9			6.3
Operating Income (Loss)	155.2			161.8			(6.6		)
Interest Expense	(45.5		)	(39.8		)	(5.7		)
Equity Earnings in ATC	19.4			19.4			—
Other Income	6.0			5.1			0.9
Income (Loss) Before Non-Controlling Interest and Income Taxes	135.1			146.5			(11.4		)
Income Tax Expense (Benefit)	38.0			50.4			(12.4		)
Net Income	97.1			96.1			1.0
Less: Non-Controlling Interest in Subsidiaries	—			—			—
Net Income Attributable to ALLETE		$97.1			$96.1			$1.0
Total Assets		$3,253.4			$2,962.4			$291.0
Capital Additions		$432.2			$418.2			$14.0

NOTE 2. BUSINESS SEGMENTS (Continued)



	Consolidated			Regulated Operations			Investments and Other
Millions
2011
Operating Revenue		$928.2			$851.9			$76.3
Fuel and Purchased Power Expense	306.6			306.6			—
Operating and Maintenance Expense	381.2			301.5			79.7
Depreciation Expense	90.4			85.4			5.0
Operating Income (Loss)	150.0			158.4			(8.4		)
Interest Expense	(43.6		)	(35.8		)	(7.8		)
Equity Earnings in ATC	18.4			18.4			—
Other Income	4.4			2.6			1.8
Income (Loss) Before Non-Controlling Interest and Income Taxes	129.2			143.6			(14.4		)
Income Tax Expense (Benefit)	35.6			43.2			(7.6		)
Net Income (Loss)	93.6			100.4			(6.8		)
Less: Non-Controlling Interest in Subsidiaries	(0.2		)	—			(0.2		)
Net Income (Loss) Attributable to ALLETE		$93.8			$100.4		$(6.6)
Total Assets		$2,876.0			$2,579.8			$296.2
Capital Additions		$246.8			$228.0			$18.8



	Consolidated			Regulated Operations			Investments and Other
Millions
2010
Operating Revenue		$907.0			$835.5			$71.5
Fuel and Purchased Power Expense	325.1			325.1			—
Operating and Maintenance Expense	365.6			292.3			73.3
Depreciation Expense	80.5			76.1			4.4
Operating Income (Loss)	135.8			142.0			(6.2		)
Interest Expense	(39.2		)	(32.3		)	(6.9		)
Equity Earnings in ATC	17.9			17.9			—
Other Income	4.6			3.8			0.8
Income (Loss) Before Non-Controlling Interest and Income Taxes	119.1			131.4			(12.3		)
Income Tax Expense (Benefit)	44.3			51.6			(7.3		)
Net Income (Loss)	74.8			79.8			(5.0		)
Less: Non-Controlling Interest in Subsidiaries	(0.5		)	—			(0.5		)
Net Income (Loss) Attributable to ALLETE		$75.3			$79.8		$(4.5)
Total Assets		$2,609.1			$2,375.4			$233.7
Capital Additions		$260.0			$256.4			$3.6

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2012

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment [Text Block]

PROPERTY, PLANT AND EQUIPMENT



Property, Plant and Equipment
As of December 31	2012			2011
Millions
Regulated Utility		$3,232.9			$2,794.8
Construction Work in Progress	151.8			155.0
Accumulated Depreciation	(1,102.8		)	(1,024.6		)
Regulated Utility Plant - Net	2,281.9			1,925.2
Non-Rate Base Energy Operations	118.0			106.4
Construction Work in Progress	4.2			2.3
Accumulated Depreciation	(56.7		)	(51.4		)
Non-Rate Base Energy Operations Plant - Net	65.5			57.3
Other Plant - Net	0.2			0.2
Property, Plant and Equipment - Net		$2,347.6			$1,982.7

Depreciation is computed using the straight-line method over the estimated useful lives of the various classes of assets.



Estimated Useful Lives of Property, Plant and Equipment

Regulated Utility –	Generation	3 to 35 years	Non-Rate Base Operations	3 to 61 years
	Transmission	42 to 61 years	Other Plant	5 to 25 years
	Distribution	14 to 65 years

Asset Retirement Obligations. We recognize, at fair value, obligations associated with the retirement of certain tangible, long-lived assets that result from the acquisition, construction or development and/or normal operation of the asset. Asset retirement obligations (ARO) relate primarily to the decommissioning of our coal-fired and wind generating facilities and land reclamation at BNI Coal, and are included in other non-current liabilities on our Consolidated Balance Sheet. The associated retirement costs are capitalized as part of the related long-lived asset and depreciated over the useful life of the asset. Removal costs associated with certain distribution and transmission assets have not been recognized, as these facilities have indeterminate useful lives.

Conditional asset retirement obligations have been identified for treated wood poles and remaining polychlorinated biphenyl and asbestos-containing assets; however, removal costs have not been recognized because they are considered immaterial to our consolidated financial statements.

Long-standing ratemaking practices approved by applicable state and federal regulatory commissions have allowed provisions for future plant removal costs in depreciation rates. These plant removal cost recoveries are classified either as AROs or as a regulatory liability for non-ARO obligations. To the extent annual accruals for plant removal costs differ from accruals under approved depreciation rates, a regulatory asset has been established in accordance with the guidance for AROs. (See Note 5. Regulatory Matters.)



Asset Retirement Obligation
Millions
Obligation as of December 31, 2010		$50.3
Accretion Expense	6.4
Additional Liabilities Incurred in 2011	0.3
Obligation as of December 31, 2011	57.0
Accretion Expense	3.8
Additional Liabilities Incurred in 2012	17.1
Obligation as of December 31, 2012		$77.9

- Definition

The entire disclosure for long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. This disclosure may include property plant and equipment accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives, income statement disclosures, assets held for sale and public utility disclosures.

+ References + Details

Jointly-Owned Facilities

12 Months Ended

Dec. 31, 2012

Jointly-Owned Facilities [Abstract]

Jointly-Owned Facilities [Text Block]

JOINTLY-OWNED FACILITIES

Following are our investments in jointly-owned facilities and the related ownership percentages as of December 31, 2012:



Regulated Utility Plant	Plant in Service		Accumulated Depreciation		Construction Work in Progress		% Ownership
Millions
Boswell Unit 4		$413.1		$188.1		$25.0	80
CapX2020	22.8		0.4		25.4		9.3 - 14.7
Total		$435.9		$188.5		$50.4

We own 80 percent of the 585 MW Boswell Unit 4. While we operate the plant, certain decisions about the operations of Boswell Unit 4 are subject to the oversight of a committee on which we and WPPI Energy, the owner of the remaining 20 percent of Boswell Unit 4, have equal representation and voting rights. Each of us must provide our own financing and is obligated to pay our ownership share of operating costs. Our share of direct operating expenses of Boswell Unit 4 is included in operating expense on our Consolidated Statement of Income. We are a participant in the CapX2020 initiative to ensure reliable electric transmission and distribution in the region surrounding our rate-regulated operations in Minnesota, along with other electric cooperatives, municipals, and investor-owned utilities. We are currently participating in three CapX2020 projects with varying ownership percentages.

Regulatory Matters

12 Months Ended

Dec. 31, 2012

Regulatory Matters [Abstract]

Regulatory Matters [Text Block]

REGULATORY MATTERS

Electric Rates. Entities within our Regulated Operations segment file for periodic rate revisions with the MPUC, the FERC or the PSCW.

2010 Minnesota Rate Case. Minnesota Power’s current retail rates are based on a 2011 MPUC retail rate order, effective June 1, 2011, that allowed for a 10.38 percent return on common equity and a 54.29 percent equity ratio.

In February 2011, Minnesota Power appealed the MPUC’s interim rate decision in the Company’s 2010 rate case to the Minnesota Court of Appeals. The Company appealed the MPUC’s finding of exigent circumstances in the interim rate decision with the primary arguments being that the MPUC exceeded its statutory authority, made its decision without the support of a body of record evidence and that the decision violated public policy. The Company desires to resolve whether the MPUC’s finding of exigent circumstances was lawful for application in future rate cases. In December 2011, the Minnesota Court of Appeals concluded that the MPUC did not err in finding exigent circumstances and properly exercised its discretion in setting interim rates. On January 4, 2012, the Company filed a petition for review at the Minnesota Supreme Court (Court). On February 14, 2012, the Court granted the petition for review and oral arguments were held before the Court on October 9, 2012. A decision is expected in early 2013; however, we cannot predict the outcome at this time.

FERC-Approved Wholesale Rates. Minnesota Power’s non-affiliated municipal customers consist of 16 municipalities in Minnesota and 1 private utility in Wisconsin. SWL&P, a wholly-owned subsidiary of ALLETE, is also a private utility in Wisconsin and a customer of Minnesota Power. Minnesota Power’s formula-based contract with the City of Nashwauk is effective April 1, 2013 through June 30, 2024, and the restated formula-based contracts with the remaining 15 Minnesota municipal customers and SWL&P are effective through June 30, 2019. The rates included in these contracts are calculated using a cost-based formula methodology that is set each July 1, using estimated costs and a rate of return that is equal to our authorized rate of return for Minnesota retail customers (currently 10.38 percent). The formula-based rate methodology also provides for a yearly true-up calculation for actual costs incurred. The contract terms include a termination clause requiring a three-year notice to terminate. Under the City of Nashwauk contract, no termination notice may be given prior to July 1, 2021. Under the restated contracts, no termination notices may be given prior to June 30, 2016. A two-year cancellation notice is required for the one private non-affiliated utility in Wisconsin, and on December 31, 2011, this customer submitted a cancellation notice with termination effective on December 31, 2013. The 17 MW of average monthly demand provided to this customer is expected to be used to supply energy to prospective customers beginning in 2014.

2012 Wisconsin Rate Case. During 2012, SWL&P’s retail rates were based on a 2010 PSCW retail rate order, which was effective January 1, 2011. SWL&P’s 2013 retail rates are based on a 2012 PSCW retail rate order, effective January 1, 2013, and allows for a 10.9 percent return on common equity. The new rates reflect an average overall increase of 2.4 percent for retail customers (a 13.8 percent increase in water rates, a 1.2 percent increase in electric rates, and a 2.0 percent decrease in natural gas rates). On an annualized basis, the rate increase will generate approximately $1.7 million in additional revenue.

NOTE 5. REGULATORY MATTERS (Continued)

Rapids Energy Center. On December 19, 2012, Minnesota Power filed with the MPUC for approval to transfer the assets of Rapids Energy Center from non-rate base generation to Minnesota Power’s Regulated Operations. Rapids Energy Center is a generation facility that is located at the UPM, Blandin Paper Mill (Blandin). Minnesota Power and Blandin entered into a new electric service agreement in September 2012 which is also subject to MPUC approval. We expect a decision from the MPUC on these filings in mid-2013.

ALLETE Clean Energy. In August 2011, the Company filed with the MPUC for approval of certain affiliated interest agreements between ALLETE and ALLETE Clean Energy. These agreements relate to various relationships between the parties, including the accounting for certain shared services, as well as the transfer of transmission and wind development rights in North Dakota to ALLETE Clean Energy. These transmission and wind development rights are separate and distinct from those needed by Minnesota Power to meet Minnesota’s renewable energy standard requirements. On July 23, 2012, the MPUC issued an order approving certain administrative items related to accounting for shared services and the transfer of meteorological towers, while deferring decisions related to transmission and wind development rights pending the MPUC’s further review of Minnesota Power’s future retail electric service needs.

Boswell Mercury Emissions Reduction Plan. Minnesota Power is required to implement a mercury emissions reduction project for Boswell Unit 4 under the Minnesota Mercury Emissions Reduction and the Federal MATS rule. On August 31, 2012, Minnesota Power filed its mercury emissions reduction plan for Boswell Unit 4 with the MPUC and the MPCA. The plan proposes that Minnesota Power install pollution controls by early 2016 to address both the Minnesota mercury emissions reduction requirements and the Federal MATS rule. Costs to implement the Boswell Unit 4 mercury emissions reduction plan are included in the estimated capital expenditures required for compliance with the MATS rule and are estimated to be between $350 million and $400 million. The MPCA has 180 days to comment on the mercury emissions reduction plan, which then is reviewed by the MPUC for a decision. We expect a decision by the MPUC on the plan in the third quarter of 2013. After approval by the MPUC we anticipate filing a petition to include investments and expenditures in customer billing rates.

The Patient Protection and Affordable Care Act of 2010 (PPACA). In March 2010, the PPACA was signed into law. One of the provisions changed the tax treatment for retiree prescription drug expenses by eliminating the tax deduction for expenses that are reimbursed under Medicare Part D, beginning January 1, 2013. Based on this provision, we are subject to additional taxes in the future and were required to reverse previously recorded tax benefits which resulted in a non-recurring charge to net income of $4.0 million in 2010. In October 2010, we submitted a filing with the MPUC requesting deferral of the retail portion of the tax charge taken in 2010 resulting from the PPACA. In May 2011, the MPUC approved our request for deferral until the next rate case and as a result we recorded an income tax benefit of $2.9 million and a related regulatory asset of $5.0 million in the second quarter of 2011.

Pension. In December 2011, the Company filed a petition with the MPUC requesting a mechanism to recover the cost of capital associated with the prepaid pension asset (or liability) created by the required contributions under the pension plan in excess of (or less than) annual pension expense. The Company further requested a mechanism to defer pension expenses in excess of (or less than) those currently being recovered in base rates. On February 14, 2013, the MPUC denied the Company's petition for recovery of the pension asset and deferral of expenses outside of a general rate case. The MPUC decision does not impact the results of operations for the year ended December 31, 2012.

Regulatory Assets and Liabilities. Our regulated utility operations are subject to the accounting guidance for Regulated Operations. We capitalize incurred costs which are probable of recovery in future utility rates as regulatory assets. Regulatory liabilities represent amounts expected to be refunded or credited to customers in rates. No regulatory assets or liabilities are currently earning a return.

NOTE 5. REGULATORY MATTERS (Continued)



Regulatory Assets and Liabilities
As of December 31	2012		2011
Millions
Current Regulatory Assets (a)
Deferred Fuel		$22.5		$17.5
Total Current Regulatory Assets	22.5		17.5
Non-Current Regulatory Assets
Future Benefit Obligations Under
Defined Benefit Pension and Other Postretirement Plans	260.7		292.8
Income Taxes	36.0		28.6
Asset Retirement Obligation	12.1		9.8
Cost Recovery Riders (b)	18.5		0.7
PPACA Income Tax Deferral	5.0		5.0
Conservation Improvement Program	4.3		4.6
Other	3.7		4.4
Total Non-Current Regulatory Assets	340.3		345.9

Total Regulatory Assets		$362.8		$363.4

Non-Current Regulatory Liabilities
Income Taxes		$19.5		$21.9
Plant Removal Obligations	18.1		15.0
Wholesale and Retail Contra AFUDC	15.5		1.5
Other	7.0		5.1
Total Non-Current Regulatory Liabilities		$60.1		$43.5


(a)	Current regulatory assets are included in prepayments and other on our Consolidated Balance Sheet.


(b)	The increase in cost recovery rider regulatory assets in 2012 is primarily due to revenues related to our Bison Wind Energy Center.

Investment in ATC

12 Months Ended

Dec. 31, 2012

Investment in ATC [Abstract]

Investment in ATC [Text Block]

INVESTMENT IN ATC

Investment in ATC. Our wholly-owned subsidiary, Rainy River Energy, owns approximately 8 percent of ATC, a Wisconsin-based utility that owns and maintains electric transmission assets in parts of Wisconsin, Michigan, Minnesota, and Illinois. ATC rates are FERC-approved and are based on a 12.2 percent return on common equity dedicated to utility plant. We account for our investment in ATC under the equity method of accounting. As of December 31, 2012, our equity investment in ATC was $107.3 million ($98.9 million at December 31, 2011). On January 30, 2013, we invested an additional $0.4 million in ATC. In total, we expect to invest approximately $2.0 million throughout 2013.



ALLETE’s Interest in ATC
Year Ended December 31	2012			2011
Millions
Equity Investment Beginning Balance		$98.9			$93.3
Cash Investments	4.7			2.0
Equity in ATC Earnings	19.4			18.4
Distributed ATC Earnings	(15.7		)	(14.8		)
Equity Investment Ending Balance		$107.3			$98.9

NOTE 6. INVESTMENT IN ATC (Continued)



ATC Summarized Financial Data
Balance Sheet Data
As of December 31	2012		2011
Millions
Current Assets		$63.1		$58.7
Non-Current Assets	3,274.7		3,053.7
Total Assets		$3,337.8		$3,112.4
Current Liabilities		$251.5		$298.5
Long-Term Debt	1,550.0		1,400.0
Other Non-Current Liabilities	95.8		82.6
Members’ Equity	1,440.5		1,331.3
Total Liabilities and Members’ Equity		$3,337.8		$3,112.4



Income Statement Data
Year Ended December 31	2012		2011		2010
Millions
Revenue		$603.2		$567.2		$556.7
Operating Expense	281.0		261.6		251.1
Other Expense	84.8		81.7		85.9
Net Income		$237.4		$223.9		$219.7
ALLETE’s Equity in Net Income		$19.4		$18.4		$17.9

- Definition

The entire disclosure for equity method investments and joint ventures. Equity method investments are investments that give the investor the ability to exercise significant influence over the operating and financial policies of an investee. Joint ventures are entities owned and operated by a small group of businesses as a separate and specific business or project for the mutual benefit of the members of the group.

+ References + Details

Investments

12 Months Ended

Dec. 31, 2012

Investments [Abstract]

Investments [Text Block]

INVESTMENTS

Investments. At December 31, 2012, our long-term investment portfolio included the real estate assets of ALLETE Properties, debt and equity securities consisting primarily of securities held to fund employee benefits, and other assets consisting primarily of cash equivalents and land in Minnesota.



Investments
As of December 31	2012		2011
Millions
ALLETE Properties		$91.1		$91.3
Available-for-sale Securities	26.8		24.7
Other	25.6		16.3
Total Investments		$143.5		$132.3

NOTE 7. INVESTMENTS (Continued)



ALLETE Properties
As of December 31	2012			2011
Millions
Land Inventory Beginning Balance		$86.0			$86.0
Deeds to Collateralized Property	0.5			1.8
Land Impairment	—			(1.7		)
Cost of Sales	(0.2		)	(0.3		)
Capitalized Improvements and Other	0.2			0.2
Land Inventory Ending Balance	86.5			86.0
Long-Term Finance Receivables (net of allowances of $0.6 and $0.6)	1.4			2.0
Other	3.2			3.3
Total Real Estate Assets		$91.1			$91.3

Land Inventory. Land inventory is accounted for as held for use and is recorded at cost, unless the carrying value is determined not to be recoverable in accordance with the accounting standards for property, plant and equipment, in which case the land inventory is written down to fair value. Land values are reviewed for impairment on a quarterly basis. In 2012, impairment analysis’ of estimated future undiscounted cash flows was conducted and indicated that the cash flows were adequate to recover the carrying basis of our land inventory. Consequently, there was no impairment recorded for the year ended December 31, 2012. For the year ended December 31, 2011, a 1.7 million impairment charge was recorded.

Long-Term Finance Receivables. As of December 31, 2012, long-term finance receivables were $1.4 million net of allowance ($2.0 million net of allowance as of December 31, 2011). The decrease is primarily the result of the transfer of properties back to ALLETE Properties by deed-in-lieu of foreclosure, in satisfaction of amounts previously owed under long-term finance receivables. Long-term finance receivables are collateralized by property sold, accrue interest at market-based rates and are net of an allowance for doubtful accounts. As of December 31, 2012, we had allowance for doubtful accounts of $0.6 million ($0.6 million as of December 31, 2011).

If a purchaser defaults on a sales contract, the legal remedy is usually limited to terminating the contract and retaining the purchaser’s deposit. The property is then available for resale. Contract purchasers may incur significant costs during due diligence, planning, designing and marketing the property before the contract closes, therefore they may have substantially more at risk than the deposit.

Available-for-Sale Investments. We account for our available-for-sale portfolio in accordance with the guidance for certain investments in debt and equity securities. Our available-for-sale securities portfolio consisted of securities established to fund certain employee benefits and auction rate securities. Our auction rate securities of $6.7 million were redeemed at carrying value on January 5, 2011.



Available-For-Sale Securities
Millions		Gross Unrealized
As of December 31	Cost	Gain	(Loss)	Fair Value
2012	$27.4	$0.5	$(1.1)	$26.8
2011	$27.3	$0.1	$(2.7)	$24.7
2010	$27.4	$0.2	$(2.4)	$25.2



	Net	Gross Realized		Net Unrealized Gain (Loss) in Other
Year Ended December 31	Proceeds	Gain	(Loss)	Comprehensive Income
2012	$1.5	—	—	$1.2
2011	$7.8	—	—	$(0.3)
2010	$0.6	—	—	$0.8

Derivatives	12 Months Ended
Derivatives	Dec. 31, 2012
Derivatives [Abstract]
Derivatives [Text Block]	DERIVATIVES During the third quarter of 2011, we entered into a variable-to-fixed interest rate swap (Swap), designated as a cash flow hedge, in order to manage the interest rate risk associated with a $75.0 million Term Loan. The Term Loan has a variable interest rate equal to the one-month LIBOR plus 1.00 percent, has a maturity of August 25, 2014, and represents approximately 8 percent of the Company’s outstanding long-term debt as of December 31, 2012. (See Note 10. Short-Term and Long-Term Debt.) The Swap agreement has a notional amount equal to the underlying debt principal and matures on August 25, 2014. The Swap agreement involves the receipt of variable rate amounts in exchange for fixed rate interest payments over the life of the agreement without an exchange of the underlying notional amount. The variable rate of the Swap is equal to the one-month LIBOR and the fixed rate is equal to 0.825 percent. Cash flows from the interest rate swap are expected to be highly effective in offsetting the variable interest expense of the debt attributable to fluctuations in the one-month LIBOR interest rate over the life of the Swap. If it is determined that a derivative is not or has ceased to be effective as a hedge, the Company prospectively discontinues hedge accounting with respect to that derivative. The shortcut method is used to assess hedge effectiveness. At inception, all shortcut method requirements were satisfied; thus changes in value of the Swap designated as the hedging instrument will be deemed 100 percent effective. As a result, there was no ineffectiveness recorded for the year ended December 31, 2012. The mark-to-market fluctuation on the cash flow hedge was recorded in accumulated other comprehensive income on the Consolidated Balance Sheet. As of December 31, 2012, the fair value of the swap was a $0.7 million liability (a $0.4 million liability as of December 31, 2011) and is included in other non-current liabilities on the Consolidated Balance Sheet. Cash flows from derivative activities are presented in the same category as the item being hedged on the Consolidated Statement of Cash Flows. Amounts recorded in other comprehensive income related to cash flow hedges will be recognized in earnings when the hedged transactions occur or when it is probable that the hedged transactions will not occur. Gains or losses on interest rate hedging transactions are reflected as a component of interest expense on the Consolidated Statement of Income.

- Definition

The entire disclosure for the entity's entire derivative instruments and hedging activities. Describes an entity's risk management strategies, derivatives in hedging activities and non-hedging derivative instruments, the assets, obligations, liabilities, revenues and expenses arising therefrom, and the amounts of and methodologies and assumptions used in determining the amounts of such items.

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+ Details

Fair Value

12 Months Ended

Dec. 31, 2012

Fair Value [Abstract]

Fair Value [Text Block]

FAIR VALUE

Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We utilize market data or assumptions that market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. These inputs can be readily observable, market corroborated, or generally unobservable. We primarily apply the market approach for recurring fair value measurements and endeavor to utilize the best available information. Accordingly, we utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. These inputs, which are used to measure fair value, are prioritized through the fair value hierarchy. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement). The three levels of the fair value hierarchy are as follows:

Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reported date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. This category includes primarily mutual fund investments held to fund employee benefits.

Level 2 — Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reported date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts, such as treasury securities with pricing interpolated from recent trades of similar securities, or priced with models using highly observable inputs, such as commodity options priced using observable forward prices and volatilities. This category includes deferred compensation, fixed income securities, and derivative instruments consisting of cash flow hedges.

The following tables set forth by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of December 31, 2012 and December 31, 2011. Each asset and liability is classified based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment, which may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels. The estimated fair value of cash and cash equivalents listed on the Consolidated Balance Sheet approximates the carrying amount and therefore are excluded from the recurring fair value measures in the tables below.

NOTE 9. FAIR VALUE (Continued)



	Fair Value as of December 31, 2012
Recurring Fair Value Measures	Level 1		Level 2		Level 3	Total
Millions
Assets:
Investments
Available-for-sale Securities – Equity Securities		$18.0	—		—		$18.0
Available-for-sale Securities – Corporate Debt Securities	—			$8.8	—	8.8
Cash Equivalents	20.7		—		—	20.7
Total Fair Value of Assets		$38.7		$8.8	—		$47.5

Liabilities:
Deferred Compensation	—			$14.0	—		$14.0
Derivatives – Interest Rate Swap	—		0.7		—	0.7
Total Fair Value of Liabilities	—			$14.7	—		$14.7
Total Net Fair Value of Assets (Liabilities)		$38.7	$(5.9)		—		$32.8

There was no activity in Level 3 during the year ended December 31, 2012.



	Fair Value as of December 31, 2011
Recurring Fair Value Measures	Level 1		Level 2		Level 3	Total
Millions
Assets:
Investments
Available-for-sale Securities – Equity Securities		$17.6	—		—		$17.6
Available-for-sale Securities – Corporate Debt Securities	—			$8.2	—	8.2
Cash Equivalents	11.4		—		—	11.4
Total Fair Value of Assets		$29.0		$8.2	—		$37.2

Liabilities:
Deferred Compensation	—			$12.8	—		$12.8
Derivatives – Interest Rate Swap	—			$0.4	—		$0.4
Total Fair Value of Liabilities	—			$13.2	—		$13.2
Total Net Fair Value of Assets (Liabilities)		$29.0	$(5.0)		—		$24.0



Recurring Fair Value Measures Activity in Level 3	Debt Securities Issued by States of the United States (ARS)
Millions
Balance as of December 31, 2010		$6.7
Redeemed During the Period (a)	(6.7		)
Balance as of December 31, 2011		$—


(a)	The ARS were redeemed at carrying value on January 5, 2011.

The Company’s policy is to recognize transfers in and transfers out as of the actual date of the event or change in circumstances that caused the transfer. For the years ended December 31, 2012 and 2011, there were no transfers in or out of Levels 1, 2 or 3.

NOTE 9. FAIR VALUE (Continued)

Fair Value of Financial Instruments. With the exception of the items listed in the table below, the estimated fair value of all financial instruments approximates the carrying amount. The fair value for the items below were based on quoted market prices for the same or similar instruments (Level 2).



Financial Instruments	Carrying Amount		Fair Value
Millions
Long-Term Debt, Including Current Portion
December 31, 2012		$1,018.1		$1,143.7
December 31, 2011		$863.3		$966.4

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13504-108611

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15B
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44A, 44B
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 17-22, 27, 28
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15A
-Subparagraph a-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15C, 15D
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32, 33, 34
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 3, 10, 14, 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Short-term and Long-term Debt

12 Months Ended

Dec. 31, 2012

Short-Term and Long-Term Debt [Abstract]

Short-Term and Long-Term Debt [Text Block]

SHORT-TERM AND LONG-TERM DEBT

Short-Term Debt. Total short-term debt outstanding as of December 31, 2012, was $84.5 million ($6.5 million at December 31, 2011) and consisted of long-term debt due within one year and notes payable. As of December 31, 2012, short-term debt increased from December 31, 2011, primarily due to $60.0 million of long-term debt maturing in April 2013.

As of December 31, 2012, we had bank lines of credit aggregating $406.4 million ($256.4 million at December 31, 2011), of which $150.0 million expires in January 2014, and $250.0 million expires in June 2015. These bank lines of credit are available to provide short-term bank loans and liquidity support for ALLETE’s commercial paper program and to issue up to $50.0 million in letters of credit. We had no outstanding draws on our lines of credit as of December 31, 2012 ($1.1 million at December 31, 2011).

On February 1, 2012, ALLETE entered into a $150.0 million credit agreement (Agreement) with JPMorgan Chase Bank, N.A., as administrative agent, and several other lenders that are parties thereto. The Agreement is unsecured and has a maturity date of January 31, 2014, which may be extended for one year, subject to bank approvals. Advances under the Agreement may be used for general corporate purposes, to provide liquidity support for ALLETE’s commercial paper program and to issue up to $10.0 million in letters of credit.

Long-Term Debt. Total long-term debt outstanding as of December 31, 2012, was $933.6 million ($857.9 million at December 31, 2011). The aggregate amount of long-term debt maturing during 2013 is $84.5 million ($94.8 million in 2014; $17.4 million in 2015; $21.7 million in 2016; $51.2 million in 2017; and $748.5 million thereafter). Substantially all of our electric plant is subject to the lien of the mortgage collateralizing outstanding first mortgage bonds. The mortgages contain non-financial covenants customary in utility mortgages, including restrictions on our ability to incur liens, dispose of assets, and merge with other entities.

On July 2, 2012, we issued $160.0 million of the Company’s First Mortgage Bonds (Bonds) in the private placement market in two series as follows:



Issue Date	Maturity Date	Principal Amount	Interest Rate
July 2, 2012	July 15, 2026	$75 Million	3.20%
July 2, 2012	July 15, 2042	$85 Million	4.08%

We have the option to prepay all or a portion of the 3.20 percent Bonds at our discretion at any time prior to January 15, 2026, subject to a make-whole provision, and at any time on or after January 15, 2026, at par, including, in each case, accrued and unpaid interest. We also have the option to prepay all or a portion of the 4.08 percent Bonds at our discretion at any time prior to January 15, 2042, subject to a make-whole provision, and at any time on or after January 15, 2042, at par, including, in each case, accrued and unpaid interest. The Bonds are subject to the additional terms and conditions of our utility mortgage. In July 2012, we used a portion of the proceeds from the sale of the Bonds to redeem $6.0 million of our 6.50 percent Industrial Development Revenue Bonds and to repay $14.0 million in outstanding borrowings on our $150.0 million line of credit. The remaining proceeds were used to fund utility capital expenditures and for general corporate purposes. The Bonds were sold in reliance on an exemption from registration under Section 4(a)(2) of the Securities Act of 1933, as amended, to certain institutional accredited investors.

NOTE 10. SHORT-TERM AND LONG-TERM DEBT (Continued)



Long-Term Debt
As of December 31	2012		2011
Millions
First Mortgage Bonds
4.86% Series Due 2013		$60.0		$60.0
6.94% Series Due 2014	18.0		18.0
7.70% Series Due 2016	20.0		20.0
8.17% Series Due 2019	42.0		42.0
5.28% Series Due 2020	35.0		35.0
4.85% Series Due 2021	15.0		15.0
4.95% Pollution Control Series F Due 2022	111.0		111.0
6.02% Series Due 2023	75.0		75.0
4.90% Series Due 2025	30.0		30.0
5.10% Series Due 2025	30.0		30.0
3.20% Series Due 2026	75.0		—
5.99% Series Due 2027	60.0		60.0
5.69% Series Due 2036	50.0		50.0
6.00% Series Due 2040	35.0		35.0
5.82% Series Due 2040	45.0		45.0
4.08% Series Due 2042	85.0		—
SWL&P First Mortgage Bonds 7.25% Series Due 2013	10.0		10.0
Senior Unsecured Notes 5.99% Due 2017	50.0		50.0
Variable Demand Revenue Refunding Bonds Series 1997 A, B, and C Due 2013 – 2020	27.5		28.2
Industrial Development Revenue Bonds 6.5% Due 2025	—		6.0
Industrial Development Variable Rate Demand Refunding Revenue Bonds Series 2006 Due 2025	27.8		27.8
Unsecured Term Loan Variable Rate Due 2014	75.0		75.0
Other Long-Term Debt, 1.0% – 8.0% Due 2013 – 2037	41.8		40.3
Total Long-Term Debt	1,018.1		863.3
Less: Due Within One Year	84.5		5.4
Net Long-Term Debt		$933.6		$857.9

Financial Covenants. Our long-term debt arrangements contain customary covenants. In addition, our lines of credit and letters of credit supporting certain long-term debt arrangements contain financial covenants. Our compliance with financial covenants is not dependent on debt ratings. The most restrictive covenant requires ALLETE to maintain a ratio of its Indebtedness to Total Capitalization (as the amounts are calculated in accordance with the respective long-term debt arrangements) of less than or equal to 0.65 to 1.00 measured quarterly. As of December 31, 2012, our ratio was approximately 0.46 to 1.00. Failure to meet this covenant would give rise to an event of default if not cured after notice from the lender, in which event ALLETE may need to pursue alternative sources of funding. Some of ALLETE’s debt arrangements contain “cross-default” provisions that would result in an event of default if there is a failure under other financing arrangements to meet payment terms or to observe other covenants that would result in an acceleration of payments due. As of December 31, 2012, ALLETE was in compliance with its financial covenants.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References + Details

Commitments, Guarantees and Contingencies

12 Months Ended

Dec. 31, 2012

Commitments, Guarantees and Contingencies [Abstract]

Commitments, Guarantees and Contingencies [Text Block]

COMMITMENTS, GUARANTEES AND CONTINGENCIES

Power Purchase Agreements. Our long-term PPAs have been evaluated under the accounting guidance for variable interest entities. We have determined that either we have no variable interest in the PPAs, or where we do have variable interests, we are not the primary beneficiary; therefore, consolidation is not required. These conclusions are based on the fact that we do not have both control over activities that are most significant to the entity and an obligation to absorb losses or receive benefits from the entity’s performance. Our financial exposure relating to these PPAs is limited to our capacity and energy payments.

NOTE 11. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued)

Power Purchase Agreements (Continued)

Square Butte PPA. Minnesota Power has a PPA with Square Butte that extends through 2026 (Agreement). It provides a long-term supply of energy to customers in our electric service territory and enables Minnesota Power to meet reserve requirements. Square Butte, a North Dakota cooperative corporation, owns a 455 MW coal-fired generating unit (Unit) near Center, North Dakota. The Unit is adjacent to a generating unit owned by Minnkota Power, a North Dakota cooperative corporation whose Class A members are also members of Square Butte. Minnkota Power serves as the operator of the Unit and also purchases power from Square Butte.

Minnesota Power is obligated to pay its pro rata share of Square Butte’s costs based on Minnesota Power’s entitlement to Unit output. Our output entitlement under the Agreement is 50 percent for the remainder of the contract, subject to the provisions of the Minnkota Power sales agreement described below. Minnesota Power’s payment obligation will be suspended if Square Butte fails to deliver any power, whether produced or purchased, for a period of one year. Square Butte’s costs consist primarily of debt service, operating and maintenance, depreciation and fuel expenses. As of December 31, 2012, Square Butte had total debt outstanding of $416.9 million. Annual debt service for Square Butte is expected to be approximately $44 million in each of the next five years, 2013 through 2017, of which Minnesota Power’s obligation is 50 percent. Fuel expenses are recoverable through our fuel adjustment clause and include the cost of coal purchased from BNI Coal, under a long-term contract.

Minnesota Power’s cost of power purchased from Square Butte during 2012 was $67.1 million ($61.2 million in 2011; $55.2 million in 2010). This reflects Minnesota Power’s pro rata share of total Square Butte costs based on the 50 percent output entitlement. Included in this amount was Minnesota Power’s pro rata share of interest expense of $11.1 million in 2012 ($11.1 million in 2011; $10.2 million in 2010). Minnesota Power’s payments to Square Butte are approved as a purchased power expense for ratemaking purposes by both the MPUC and the FERC.

Minnkota Power Sales Agreement. In December 2009, Minnesota Power entered into a power sales agreement with Minnkota Power. Under the power sales agreement, Minnesota Power will sell a portion of its output from Square Butte to Minnkota Power, resulting in Minnkota Power’s net entitlement increasing and Minnesota Power’s net entitlement decreasing until Minnesota Power’s share is eliminated at the end of 2025.

No power will be sold under the 2009 agreement until Minnkota Power has placed in service a new AC transmission line, which is anticipated to occur in late 2013. This new AC transmission line will allow Minnkota Power to transmit its entitlement from Square Butte directly to its customers, which in turn will enable Minnesota Power the ability to transmit additional wind generation on the existing DC transmission line.

Minnkota Power PPA. On December 12, 2012, Minnesota Power entered into a long-term PPA with Minnkota Power. Under this agreement Minnesota Power will purchase 50 MW of capacity and the energy associated with that capacity over the term June 1, 2016 through May 31, 2020. The agreement includes a fixed capacity charge and energy pricing that escalates at a fixed rate annually over the term.

Oliver Wind I and II PPAs. In 2006 and 2007, Minnesota Power entered into two long-term wind PPAs with an affiliate of NextEra Energy, Inc. to purchase the output from Oliver Wind I (50 MW) and Oliver Wind II (48 MW)—wind facilities located near Center, North Dakota. Each agreement is for 25 years and provides for the purchase of all output from the facilities at fixed energy prices. There are no fixed capacity charges and we only pay for energy as it is delivered to us.

Manitoba Hydro PPAs. Minnesota Power has a long-term PPA with Manitoba Hydro that expires in April 2015. Under this agreement Minnesota Power is purchasing 50 MW of capacity and the energy associated with that capacity. Both the capacity price and the energy price are adjusted annually by the change in a governmental inflationary index.

Minnesota Power has a separate long-term PPA with Manitoba Hydro to purchase surplus energy through April 2022. This energy-only agreement primarily consists of surplus hydro energy on Manitoba Hydro’s system that is delivered to Minnesota Power on a non-firm basis. The pricing is based on forward market prices. Under this agreement, Minnesota Power will purchase at least one million MWh of energy over the contract term.

NOTE 11. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued)

Power Purchase Agreements (Continued)

In May 2011, Minnesota Power and Manitoba Hydro signed an additional PPA. The PPA calls for Manitoba Hydro to sell 250 MW of capacity and energy to Minnesota Power for 15 years beginning in 2020 and is subject to construction of additional transmission capacity between Manitoba and the U.S., along with construction of new hydroelectric generating capacity in Manitoba. The capacity price is adjusted annually until 2020 by a change in a governmental inflationary index. The energy price is based on a formula that includes an annual fixed price component adjusted for a change in a governmental inflationary index and a natural gas index, as well as market prices.

In February 2012, Minnesota Power and Manitoba Hydro proposed construction of the Great Northern Transmission Line, a 500 kV transmission line between Manitoba and Minnesota’s Iron Range in order to strengthen the electric grid, enhance regional reliability and promote a greater exchange of sustainable energy, which is targeted to be in service in 2020. Total project cost and cost allocations are still to be determined.The Great Northern Transmission Line is subject to various federal and state regulatory approvals. In addition, Manitoba Hydro must obtain regulatory and governmental approvals related to new transmission lines and hydroelectric generation development in Canada.

North Dakota Wind Development. Minnesota Power uses the 465-mile, 250 kV DC transmission line that runs from Center, North Dakota, to Duluth, Minnesota to transport increasing amounts of wind energy from North Dakota while gradually phasing out coal-based electricity delivered to our system over this transmission line from Square Butte’s lignite coal-fired generating unit.

Our Bison Wind Energy Center in North Dakota consists of 292 MW of nameplate capacity. Bison 1 is an 82 MW wind facility in North Dakota, which was completed in two phases. The first phase was completed in 2010, and the second phase was completed in January 2012. The project also included construction of a 22-mile, 230 kV transmission line. Bison 1 had a total project cost of $174.9 million through December 31, 2012, including additional costs related to land restoration and completion of remaining associated upgrades to the 250 kV DC transmission line.

The 105 MW Bison 2 and 105 MW Bison 3 wind facilities in North Dakota were completed in December 2012. Total project costs for Bison 2 and Bison 3 were $148.6 million and $149.8 million, respectively, through December 31, 2012. In September 2011 and November 2011, the MPUC approved Minnesota Power’s petitions seeking cost recovery for investments and expenditures related to Bison 2 and Bison 3, respectively.

Current customer billing rates were approved by the MPUC in a November 2011 order and are based on investments and expenditures associated with Bison 1. We anticipate filing a cost recovery petition with the MPUC in the first half of 2013 to update customer billing rates for Bison 1 and to include investments and expenditures associated with Bison 2 and Bison 3.

Coal, Rail and Shipping Contracts. We have coal supply agreements providing for the purchase of a significant portion of our coal requirements with expiration dates through 2014. We also have coal transportation agreements in place for the delivery of a significant portion of our coal requirements with expiration dates through 2015. Our minimum annual payment obligation under these supply and transportation agreements is $51.4 million for 2013 and $0.8 million for 2014. Our minimum annual payment obligation will increase when annual nominations are made for coal deliveries in future years. The delivered costs of fuel for Minnesota Power’s generation are recoverable from Minnesota Power’s utility customers through the fuel adjustment clause.

Leasing Agreements. BNI Coal is obligated to make lease payments for a dragline totaling $2.8 million annually for the lease term which expires in 2027. BNI Coal has the option at the end of the lease term to renew the lease at fair market value, to purchase the dragline at fair market value, or to surrender the dragline and pay a $3.0 million termination fee. We also lease other properties and equipment under operating lease agreements with terms expiring through 2016. The aggregate amount of minimum lease payments for all operating leases is $11.5 million in 2013, $11.7 million in 2014, $11.4 million in 2015, $9.3 million in 2016, $8.5 million in 2017 and $35.0 million thereafter. Total rent and lease expense was $11.5 million in 2012 ($9.4 million in 2011; $9.4 million in 2010).

Transmission. We continue to make investments in Upper Midwest transmission opportunities that strengthen or enhance the regional transmission grid. This includes the CapX2020 initiative, investments in our own transmission assets, investments in other regional transmission assets (individually or in combination with others), and our investment in ATC.

NOTE 11. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued)

Transmission (Continued)

Transmission Investments. We have an approved cost recovery rider in place for certain transmission investments and expenditures and the continued use of our 2009 billing factor was approved by the MPUC in May 2011. The billing factor allows us to charge our retail customers on a current basis for the costs of constructing certain transmission facilities plus a return on the capital invested. In June 2011, we filed an updated billing factor that includes additional transmission expenditures, which we expect to be approved in the first quarter of 2013.

CapX2020. Minnesota Power is a participant in the CapX2020 initiative which represents an effort to ensure electric transmission and distribution reliability in Minnesota and the surrounding region for the future. CapX2020, which consists of electric cooperatives, municipal and investor-owned utilities, including Minnesota’s largest transmission owners, has assessed the transmission system and projected growth in customer demand for electricity through 2020. Studies show that the region’s transmission system will require major upgrades and expansion to accommodate increased electricity demand as well as support renewable energy expansion through 2020.

Minnesota Power is participating in three CapX2020 projects: the Fargo, North Dakota to St. Cloud, Minnesota project, the Monticello, Minnesota to St. Cloud, Minnesota project, which together total a 238-mile, 345 kV line from Fargo, North Dakota to Monticello, Minnesota, and the 70-mile, 230 kV line between Bemidji, Minnesota and Minnesota Power’s Boswell Energy Center near Grand Rapids, Minnesota. The 28-mile 345 kV line between Monticello and St. Cloud was placed into service in December 2011 and the 70-mile 230 kV line between Bemidji, Minnesota and Minnesota Power’s Boswell Energy Center near Grand Rapids, Minnesota was placed into service in September 2012. In June 2011, the MPUC approved the route permit for the Minnesota portion of the Fargo to St. Cloud project. The North Dakota permitting process was completed on August 12, 2012. The entire 238-mile, 345 kV line from Fargo to Monticello is expected to be in service by 2015.

Based on projected costs of the three transmission lines and the allocation agreements among participating utilities, Minnesota Power plans to invest between $100 million and $110 million in the CapX2020 initiative through 2015. A total of $48.2 million was spent through December 31, 2012, of which $37.3 million related to the Fargo, North Dakota to Monticello, Minnesota projects and $10.9 million related to the Bemidji, Minnesota to Minnesota Power’s Boswell Energy Center project ($27.8 million as of December 31, 2011 of which $20.4 million related to the Fargo, North Dakota to Monticello, Minnesota projects and $7.4 million related to the Bemidji, Minnesota to Minnesota Power’s Boswell Energy Center project). As future CapX2020 projects are identified, Minnesota Power may elect to participate on a project-by-project basis.

Environmental Matters

Our businesses are subject to regulation of environmental matters by various federal, state and local authorities. Currently, a number of regulatory changes to the Clean Air Act, the Clean Water Act and various waste management requirements are under consideration by both Congress and the EPA. Minnesota Power’s fossil fuel facilities will likely be subject to regulation under these proposals. Our intention is to reduce our exposure to these requirements by reshaping our generation portfolio over time to reduce our reliance on coal.

We consider our businesses to be in substantial compliance with currently applicable environmental regulations and believe all necessary permits to conduct such operations have been obtained. Due to expected future restrictive environmental requirements imposed through legislation and/or rulemaking, we anticipate that potential expenditures for environmental matters will be material and will require significant capital investments. Minnesota Power has evaluated various environmental compliance scenarios using possible ranges of future environmental regulations to project power supply trends and impacts on customers.

We review environmental matters on a quarterly basis. Accruals for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated, based on current law and existing technologies. Accruals are adjusted as assessment and remediation efforts progress or as additional technical or legal information becomes available. Accruals for environmental liabilities are included in the Consolidated Balance Sheet at undiscounted amounts and exclude claims for recoveries from insurance or other third parties. Costs related to environmental contamination treatment and cleanup are charged to expense unless recoverable in rates from customers.

Air. The electric utility industry is heavily regulated both at the federal and state level to address air emissions. Minnesota Power’s generating facilities mainly burn low-sulfur western sub-bituminous coal. All of Minnesota Power’s coal-fired generating facilities are equipped with pollution control equipment such as scrubbers, bag houses and low NO_X technologies. Under currently applicable environmental regulations, these facilities are substantially compliant with applicable emission requirements.

NOTE 11. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued)

Environmental Matters (Continued)

New Source Review (NSR). In August 2008, Minnesota Power received a Notice of Violation (NOV) from the EPA asserting violations of the NSR requirements of the Clean Air Act at Boswell Units 1, 2, 3 and 4 and Laskin Unit 2. The NOV asserts that seven projects undertaken at these coal-fired plants between the years 1981 and 2000 should have been reviewed under the NSR requirements and that the Boswell Unit 4 Title V permit was violated. In April 2011, Minnesota Power received a NOV alleging that two projects undertaken at Rapids Energy Center in 2004 and 2005 should have been reviewed under the NSR requirements and that the Rapids Energy Center’s Title V permit was violated. Minnesota Power believes the projects specified in the NOVs were in full compliance with the Clean Air Act, NSR requirements and applicable permits. Resolution of the NOVs could result in civil penalties, which we do not believe will be material to our results of operations, and the installation of additional pollution control equipment, some of which is already planned or which has been completed to comply with other regulatory requirements. We are engaged in discussions with the EPA regarding resolution of these matters, but we are unable to estimate the expenditures, or range of expenditures that may be required upon resolution. Any costs of installing additional pollution control equipment would likely be eligible for recovery in rates over time subject to regulatory approval in a rate proceeding.

Cross-State Air Pollution Rule (CSAPR). In July 2011, the EPA issued the CSAPR, which replaced the EPA’s 2005 CAIR. However, on August 21, 2012, a three judge panel of the District of Columbia Circuit Court of Appeals vacated the CSAPR, ordering that the CAIR remain in effect while a CSAPR replacement rule is promulgated. The EPA and other parties to the case have until April 24, 2013, to request that the Supreme Court review the matter. The CSAPR would have required states in the CSAPR region, including Minnesota, to significantly improve air quality by reducing power plant emissions that contribute to ozone and/or fine particle pollution in other states. The CSAPR did not directly require the installation of controls. Instead, the rule would have required facilities to have sufficient emission allowances to cover their emissions on an annual basis. These allowances would have been allocated to facilities from each state’s annual budget and would also have been able to be bought and sold.

The CAIR regulations similarly require certain states to improve air quality by reducing power plant emissions that contribute to ozone and/or fine particle pollution in other states. The CAIR also created an allowance allocation and trading program rather than specifying pollution controls. Minnesota participation in the CAIR was stayed by EPA administrative action while the EPA completed a review of air quality modeling issues in conjunction with the development of a final replacement rule. While the CAIR remains in effect, Minnesota participation in the CAIR will continue to be stayed. It remains uncertain if emission restrictions similar to those contained in the CSAPR will become effective for Minnesota utilities due to the August 2012 District of Columbia Circuit Court of Appeals decision.

Since 2006, we have significantly reduced emissions at our Laskin, Taconite Harbor and Boswell generating units. Based on our expected generation, these emission reductions would have satisfied Minnesota Power’s SO₂ and NO_X emission compliance obligations with respect to the EPA-allocated CSAPR allowances for 2012. Minnesota Power will continue to track the EPA activity related to promulgation of a CSAPR replacement rule. We are unable to predict any additional compliance costs we might incur if the CSAPR is reinstated or if a CSAPR replacement rule is promulgated.

Regional Haze. The federal Regional Haze Rule requires states to submit SIPs to the EPA to address regional haze visibility impairment in 156 federally-protected parks and wilderness areas. Under the first phase of the Regional Haze Rule, certain large stationary sources, put in place between 1962 and 1977, with emissions contributing to visibility impairment, are required to install emission controls, known as Best Available Retrofit Technology (BART). We have two steam units, Boswell Unit 3 and Taconite Harbor Unit 3, that are subject to BART requirements.

The MPCA requested that companies with BART-eligible units complete and submit a BART emissions control retrofit study, which was completed for Taconite Harbor Unit 3 in November 2008. The retrofit work completed in 2009 at Boswell Unit 3 meets the BART requirements for that unit. In December 2009, the MPCA approved the Minnesota SIP for submittal to the EPA for its review and approval. The Minnesota SIP incorporates information from the BART emissions control retrofit studies that were completed as requested by the MPCA.

NOTE 11. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued)

Environmental Matters (Continued)

In December 2011, the EPA published in the Federal Register a proposal to approve the trading program in the CSAPR as an alternative to determining BART. However, as a result of the August 2012 District of Columbia Circuit Court of Appeals decision to vacate the CSAPR (See CSAPR), Minnesota Power is now evaluating whether significant additional expenditures at Taconite Harbor Unit 3 will be required to comply with BART requirements under the Regional Haze Rule. If additional regional haze related controls are ultimately required, Minnesota Power will have up to five years from the final rule promulgation to bring Taconite Harbor Unit 3 into compliance with the Regional Haze Rule requirements. It is uncertain what controls would ultimately be required at Taconite Harbor Unit 3 under this scenario. On January 30, 2013, Minnesota Power announced “EnergyForward”, a strategic plan for assuring reliability, protecting affordability and further improving environmental performance. The plan includes retiring Taconite Harbor Unit 3 in 2015, subject to MPUC approval.

Mercury and Air Toxics Standards (MATS) Rule (formerly known as the Electric Generating Unit Maximum Achievable Control Technology (MACT) Rule). Under Section 112 of the Clean Air Act, the EPA is required to set emission standards for hazardous air pollutants (HAPs) for certain source categories. The EPA published the final MATS rule in the Federal Register on February 16, 2012, addressing such emissions from coal-fired utility units greater than 25 MW. There are currently 187 listed HAPs that the EPA is required to evaluate for establishment of MACT standards. In the final MATS rule, the EPA established categories of HAPs, including mercury, trace metals other than mercury, acid gases, dioxin/furans, and organics other than dioxin/furans. The EPA also established emission limits for the first three categories of HAPs, and work practice standards for the remaining categories. Affected sources must be in compliance with the rule by April 2015. States have the authority to grant sources a one-year extension. Minnesota Power was notified by the MPCA that they have approved Minnesota Power’s request of an additional year extending the date of compliance for the Boswell Unit 4 retrofit to April 1, 2016. Compliance at our Boswell Unit 4 to address the final MATS rule is expected to result in capital expenditures totaling between $350 million and $400 million through 2016. Our “EnergyForward” plan also includes the conversion of Laskin Units 1 and 2 to natural gas addressing the MATS requirements.

EPA National Emission Standards for Hazardous Air Pollutants for Major Sources: Industrial, Commercial and Institutional Boilers and Process Heaters. In March 2011, a final rule was published in the Federal Register for industrial boiler maximum achievable control technology (Industrial Boiler MACT). The rule was stayed by the EPA in May 2011, to allow the EPA time to consider additional comments received. The EPA re-proposed the rule in December 2011. On January 9, 2012, the United States District Court for the District of Columbia ruled that the EPA stay of the Industrial Boiler MACT was unlawful, effectively reinstating the March 2011 rule and associated compliance deadlines. A final rule based on the December 2011 proposal, which supersedes the March 2011 rule, was released on December 21, 2012. Major sources have three years to achieve compliance with the final rule. Minnesota Power is in the process of assessing the impact of this rule on our affected units including the Hibbard Renewable Energy Center and Rapids Energy Center. Costs for complying with the final rule cannot be estimated at this time.

Minnesota Mercury Emissions Reduction Act. Under the 2006 Minnesota Mercury Emissions Reduction Act, Minnesota Power is required to implement a mercury emissions reduction project for Boswell Unit 4 by December 31, 2018. On August 31, 2012, Minnesota Power filed its mercury emissions reduction plan for Boswell Unit 4 with the MPUC and the MPCA. The plan proposes that Minnesota Power install pollution controls to address both the Minnesota mercury emissions reduction requirements and the MATS rule, which also regulates mercury emissions. Minnesota Power's request of an additional year extending the date of compliance for the Boswell Unit 4 retrofit to April 1, 2016, was approved by the MPCA. Costs to implement the Boswell Unit 4 mercury emissions reduction plan are included in the estimated capital expenditures required for compliance with the MATS rule discussed above.

Proposed and Finalized National Ambient Air Quality Standards (NAAQS). The EPA is required to review the NAAQS every five years. If the EPA determines that a state’s air quality is not in compliance with a NAAQS, the state is required to adopt plans describing how it will reduce emissions to attain the NAAQS. These state plans often include more stringent air emission limitations on sources of air pollutants than the NAAQS. Four NAAQS have either recently been revised or are currently proposed for revision, as described below.

Ozone NAAQS. The EPA has proposed to more stringently control emissions that result in ground level ozone. In January 2010, the EPA proposed to revise the 2008 eight-hour ozone standard and to adopt a secondary standard for the protection of sensitive vegetation from ozone-related damage. The EPA was scheduled to decide upon the 2008 eight-hour ozone standard in July 2011, but has since announced that it is deferring revision of this standard until 2013.

NOTE 11. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued)

Environmental Matters (Continued)

Particulate Matter NAAQS.The EPA finalized the NAAQS Particulate Matter standards in September 2006. Since then, the EPA has established a more stringent 24-hour average fine particulate matter (PM_2.5) standard; the annual PM_2.5 standard and the 24-hour coarse particulate matter standard have remained unchanged. The United States Court of Appeals for the District of Columbia Circuit remanded the annual PM_2.5 standard to the EPA, requiring consideration of lower annual standard values. The EPA proposed new PM_2.5 standards on June 14, 2012.

On December 14, 2012, the EPA confirmed in a final rule that the current annual PM_2.5 standard, which has been in place since 1997, will be lowered, while retaining the current 24-hour PM_2.5standard. To implement the new lower annual PM_2.5standard, the EPA is also revising aspects of relevant monitoring, designations and permitting requirements. New projects and permits must comply with the new lower standard, and compliance with the NAAQS at the facility level is generally demonstrated by modeling. To bridge the transition to the lower standard, the EPA is finalizing a grandfathering provision to ensure that projects and pending permits already underway are not unduly delayed.

Under the final rule, states will be responsible for additional PM_2.5 monitoring, which will likely be accomplished by relocation or repurposing of existing monitors. States are expected to propose attainment designations by December 2013, based on already available monitoring data. The EPA believes that most U.S. counties currently already meet the new standard and plans to finalize designations of attainment by December 2014. For those counties that the EPA does not designate as having already met the requirements of the new standard, specific dates for required attainment will depend on technology availability, state permitting goals, potential legal challenges and other factors.

SO₂ and NO₂ NAAQS. During 2010, the EPA finalized new one-hour NAAQS for SO₂ and NO₂. Ambient monitoring data indicates that Minnesota will likely be in compliance with these new standards; however, the one-hour SO₂ NAAQS also require the EPA to evaluate modeling data to determine attainment. The EPA has notified states that their SIPs for attainment of the standard will be required to be submitted to the EPA for approval by June 2013 but will not be required to include the evaluation of modeling data until 2017.

In late 2011, the MPCA initiated modeling activities that included approximately 65 sources within Minnesota that emit greater than 100 tons of SO₂ per year. However, on April 12, 2012, the MPCA notified Minnesota Power that such modeling had been suspended as a result of the EPA’s announcement that the June 2013 SIP submittals would no longer require modeling demonstrations for states, such as Minnesota, where ambient monitors indicate compliance with the new standard. The MPCA is awaiting updated EPA guidance and will communicate with affected sources once the MPCA has more information on how the state will meet the EPA’s SIP requirements. Currently, compliance with these new NAAQS is expected to be required as early as 2017. The costs for complying with the final standards cannot be estimated at this time.

Climate Change. The scientific community generally accepts that emissions of GHGs are linked to global climate change. Climate change creates physical and financial risk. Physical risks could include, but are not limited to: increased or decreased precipitation and water levels in lakes and rivers; increased temperatures; and the intensity and frequency of extreme weather events. These all have the potential to affect the Company’s business and operations. We are addressing climate change by taking the following steps that also ensure reliable and environmentally compliant generation resources to meet our customers’ requirements:


•	Expand our renewable energy supply;


•	Provide energy conservation initiatives for our customers and engage in other demand side efforts;


•	Support research of technologies to reduce carbon emissions from generation facilities and carbon sequestration efforts; and


•	Evaluating and developing less carbon intense future generating assets such as efficient and flexible natural gas generating facilities.

EPA Regulation of GHG Emissions. In May 2010, the EPA issued the final Prevention of Significant Deterioration (PSD) and Title V Greenhouse Gas Tailoring Rule (Tailoring Rule). The Tailoring Rule establishes permitting thresholds required to address GHG emissions for new facilities, at existing facilities that undergo major modifications and at other facilities characterized as major sources under the Clean Air Act’s Title V program. For our existing facilities, the rule does not require amending our existing Title V operating permits to include GHG requirements. However, GHG requirements are likely to be added to our existing Title V operating permits by the MPCA as these permits are renewed or amended.

NOTE 11. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued)

Environmental Matters (Continued)

In late 2010, the EPA issued guidance to permitting authorities and affected sources to facilitate incorporation of the Tailoring Rule permitting requirements into the Title V and PSD permitting programs. The guidance stated that the project-specific, top-down BACT determination process used for other pollutants will also be used to determine BACT for GHG emissions. Through sector-specific white papers, the EPA also provided examples and technical summaries of GHG emission control technologies and techniques the EPA considers available or likely to be available to sources. It is possible that these control technologies could be determined to be BACT on a project-by-project basis.

On March 28, 2012, the EPA announced its proposed rule to apply CO₂ emission New Source Performance Standards (NSPS) to new fossil fuel-fired electric generating units. The proposed NSPS apply only to new or re-powered units and were open for public comment through June 25, 2012. It is anticipated that the EPA will issue NSPS for existing fossil fuel-fired generating units in the future. We cannot predict what CO₂ control measures, if any, may be required by such NSPS.

Legal challenges have been filed with respect to the EPA’s regulation of GHG emissions, including the Tailoring Rule. On June 26, 2012, the United States District Court for the District of Columbia upheld most of the EPA’s proposed regulations, including the Tailoring Rule criteria, finding that the Clean Air Act compels the EPA to regulate in the manner the EPA proposed. Comments to the permitting guidance were submitted by Minnesota Power and others and may be addressed by the EPA in the form of revised guidance documents.

We are unable to predict the GHG emission compliance costs we might incur; however, the costs could be material. We would seek recovery of any additional costs through cost recovery riders or in a general rate case.

Water. The Clean Water Act requires NPDES permits be obtained from the EPA (or, when delegated, from individual state pollution control agencies) for any wastewater discharged into navigable waters. We have obtained all necessary NPDES permits, including NPDES storm water permits for applicable facilities, to conduct our operations.

Clean Water Act - Aquatic Organisms. In April 2011, the EPA published in the Federal Register proposed regulations under Section 316(b) of the Clean Water Act that set standards applicable to cooling water intake structures for the protection of aquatic organisms. The proposed regulations would require existing large power plants and manufacturing facilities that withdraw greater than 25 percent of water from adjacent water bodies for cooling purposes and have a design intake flow of greater than 2 million gallons per day to limit the number of aquatic organisms that are killed when they are pinned against the facility’s intake structure or that are drawn into the facility’s cooling system. The Section 316(b) standards would be implemented through NPDES permits issued to the covered facilities. The Section 316(b) proposed rule comment period ended in August 2011 and the EPA is obligated to finalize the rule by June 27, 2013. We are unable to predict the compliance costs we might incur under the final rule; however, the costs could be material. We would seek recovery of any additional costs through cost recovery riders or in a general rate case.

Steam Electric Power Generating Effluent Guidelines. In late 2009, the EPA announced that it will be reviewing and reissuing the federal effluent guidelines for steam electric stations. These are the underlying federal water discharge rules that apply to all steam electric stations. It is expected that the EPA will publish the proposed new rule in April 2013 and a final rule in 2014. As part of the review phase for this new rule, the EPA issued an Information Collection Request (ICR) in June 2010, to most thermal electric generating stations in the country, including all five of Minnesota Power’s generating stations. The ICR was completed and submitted to the EPA in September 2010, for Boswell, Laskin, Taconite Harbor, Hibbard and Rapids Energy Center. The ICR was designed to gather extensive information on the nature and extent of all water discharge and related wastewater handling at power plants. The information gathered through the ICR will form a basis for development of the eventual new rule, which could include more restrictive requirements on wastewater discharge, flue gas desulfurization, and wet ash handling operations. We are unable to predict the costs we might incur to comply with potential future water discharge regulations at this time.

Solid and Hazardous Waste. The Resource Conservation and Recovery Act of 1976 regulates the management and disposal of solid and hazardous wastes. We are required to notify the EPA of hazardous waste activity and, consequently, routinely submit the necessary reports to the EPA.

NOTE 11. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued)

Environmental Matters (Continued)

Coal Ash Management Facilities. Minnesota Power generates coal ash at all five of its coal-fired electric generating facilities. Two facilities store ash in onsite impoundments (ash ponds) with engineered liners and containment dikes. Another facility stores dry ash in a landfill with an engineered liner and leachate collection system. Two facilities generate a combined wood and coal ash that is either land applied as an approved beneficial use or trucked to state permitted landfills. In June 2010, the EPA proposed regulations for coal combustion residuals generated by the electric utility sector. The proposal sought comments on three general regulatory schemes for coal ash. Comments on the proposed rule were due in November 2010. It is estimated that the final rule will be published in 2013. We are unable to predict the compliance costs we might incur; however, the costs could be material. We would seek recovery of any additional costs through cost recovery riders or in a general rate case.

Other Matters

BNI Coal. As of December 31, 2012, BNI Coal had surety bonds outstanding of $29.8 million related to the reclamation liability for closing costs associated with its mine and mine facilities. Although the coal supply agreements obligate the customers to provide for the closing costs, additional assurance is required by federal and state regulations. In addition to the surety bonds, BNI Coal has secured a letter of credit with CoBANK ACB for an additional $2.6 million to provide for BNI Coal’s total reclamation liability, which is currently estimated at $32.4 million. BNI Coal does not believe it is likely that any of these outstanding surety bonds or the letter of credit will be drawn upon.

ALLETE Properties. As of December 31, 2012, ALLETE Properties, through its subsidiaries, had surety bonds outstanding and letters of credit to governmental entities totaling $10.2 million primarily related to development and maintenance obligations for various projects. The estimated cost of the remaining development work is approximately $7.4 million, of which $0.6 million is the contractual obligation of land purchasers. ALLETE Properties does not believe it is likely that any of these outstanding surety bonds or letters of credit will be drawn upon.

Community Development District Obligations. In March 2005, the Town Center District issued $26.4 million of tax-exempt, 6 percent capital improvement revenue bonds and in May 2006, the Palm Coast Park District issued $31.8 million of tax-exempt, 5.7 percent special assessment bonds. The capital improvement revenue bonds and the special assessment bonds are payable over 31 years (by May 1, 2036 and 2037, respectively) and secured by special assessments on the benefited land. The bond proceeds were used to pay for the construction of a portion of the major infrastructure improvements in each district and to mitigate traffic and environmental impacts. The assessments were billed to the landowners beginning in November 2006 for Town Center and November 2007 for Palm Coast Park. To the extent that we still own land at the time of the assessment, we will incur the cost of our portion of these assessments, based upon our ownership of benefited property. At December 31, 2012, we owned 73 percent of the assessable land in the Town Center District (73 percent at December 31, 2011) and 93 percent of the assessable land in the Palm Coast Park District (93 percent at December 31, 2011). At these ownership levels, our annual assessments are approximately $1.4 million for Town Center and $2.1 million for Palm Coast Park. As we sell property, the obligation to pay special assessments will pass to the new landowners. In accordance with accounting guidance, these bonds are not reflected as debt on our Consolidated Balance Sheet.

Legal Proceedings. In January 2011, the Company was named as a defendant in a lawsuit in the Sixth Judicial District for the State of Minnesota by one of our customer’s (United Taconite, LLC) property and business interruption insurers. In October 2006, United Taconite experienced a fire as a result of the failure of certain electrical protective equipment. The equipment at issue in the incident was not owned, designed, or installed by Minnesota Power, but Minnesota Power had provided testing and calibration services related to the equipment. The lawsuit alleges approximately $20.0 million in damages related to the fire. The Company believes that it has strong defenses to the lawsuit and intends to vigorously assert such defenses. An accrual related to any damages that may result from the lawsuit has not been recorded as of December 31, 2012, because a potential loss is not currently probable or reasonably estimable; however, the Company believes it has adequate insurance coverage for any potential loss.

Other. We are involved in litigation arising in the normal course of business. Also in the normal course of business, we are involved in tax, regulatory and other governmental audits, inspections, investigations and other proceedings that involve state and federal taxes, safety, and compliance with regulations, rate base and cost of service issues, among other things. While the resolution of such matters could have a material effect on earnings and cash flows in the year of resolution, none of these matters are expected to materially change our present liquidity position, or have a material adverse effect on our financial condition.

- Definition

The entire disclosure for commitments and contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6449706&loc=d3e16207-108621

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6398077&loc=d3e12565-110249

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25287-109308

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 14
-Paragraph 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9, 10, 11, 12
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Common Stock and Earnings Per Share

12 Months Ended

Dec. 31, 2012

Common Stock and Earnings Per Share [Abstract]

Common Stock and Earnings Per Share [Text Block]

COMMON STOCK AND EARNINGS PER SHARE



Summary of Common Stock	Shares	Equity
	Thousands	Millions
Balance as of December 31, 2009	35,221		$613.4
Employee Stock Purchase Program	19	0.6
Invest Direct	346	11.7
Options and Stock Awards	51	4.4
Equity Issuance Program	180	6.0
Balance as of December 31, 2010	35,817		$636.1
Employee Stock Purchase Program	20	0.8
Invest Direct	437	17.2
Options and Stock Awards	109	6.7
Equity Issuance Program	400	16.0
Purchase of Non-Controlling Interest	222	8.8
Contributions to Pension	508	20.0
Balance as of December 31, 2011	37,513		$705.6
Employee Stock Purchase Program	20	0.8
Invest Direct	474	19.2
Options and Stock Awards	95	6.0
Equity Issuance Program	1,275	53.1
Balance as of December 31, 2012	39,377		$784.7

Equity Issuance Program. We entered into a distribution agreement with KCCI, Inc., in February 2008, as amended most recently on August 3, 2012, with respect to the issuance and sale of up to an aggregate of 9.6 million shares of our common stock, without par value, of which 4.5 million remain available for issuance. For the year ended December 31, 2012, 1.3 million shares of common stock were issued under this agreement resulting in net proceeds of $53.1 million. During 2011, 0.4 million shares of common stock were issued for net proceeds of $16.0 million. The shares issued in 2012 and 2011 were, and the remaining shares may be, offered for sale, from time to time, in accordance with the terms of the amended distribution agreement pursuant to Registration Statement No. 333-170289.

Earnings Per Share. The difference between basic and diluted earnings per share, if any, arises from outstanding stock options, non-vested restricted stock, and performance share awards granted under our Executive and Director Long-Term Incentive Compensation Plans. In 2012, in accordance with accounting standards for earnings per share, 0.2 million options to purchase shares of common stock were excluded from the computation of diluted earnings per share because the option exercise prices were greater than the average market prices; therefore, their effect would have been anti-dilutive (0.3 million shares were excluded in 2011 and 0.5 million in 2010).

Purchase of Non-Controlling Interest. In 2011, the remaining shares of the ALLETE Properties non-controlling interest were purchased at book value for $8.8 million by issuing 0.2 million unregistered shares of ALLETE common stock. This was accounted for as an equity transaction, and no gain or loss is recognized in net income or comprehensive income.

Contributions to Pension. In 2011, ALLETE contributed approximately 0.5 million shares of ALLETE common stock to its pension plan. These shares of ALLETE common stock were contributed in reliance upon an exemption available pursuant to Section 4(a)(2) of the Securities Act of 1933 and had an aggregate value of $20.0 million when contributed.

NOTE 12. COMMON STOCK AND EARNINGS PER SHARE (Continued)



Reconciliation of Basic and Diluted
Earnings Per Share			Dilutive
Year Ended December 31	Basic		Securities	Diluted
Millions Except Per Share Amounts
2012
Net Income Attributable to ALLETE		$97.1			$97.1
Average Common Shares	37.6		—	37.6
Earnings Per Share		$2.59			$2.58
2011
Net Income Attributable to ALLETE		$93.8			$93.8
Average Common Shares	35.3		0.1	35.4
Earnings Per Share		$2.66			$2.65
2010
Net Income Attributable to ALLETE		$75.3			$75.3
Average Common Shares	34.2		0.1	34.3
Earnings Per Share		$2.20			$2.19

Other Income (Expense)

12 Months Ended

Dec. 31, 2012

Other Income (Expense) [Abstract]

Other Income (Expense) [Text Block]

OTHER INCOME (EXPENSE)



Year Ended December 31	2012		2011		2010
Millions
AFUDC – Equity		$5.1		$2.5		$4.2
Investment and Other Income	0.9		1.9		0.4
Total Other Income		$6.0		$4.4		$4.6

Income Tax Expense

12 Months Ended

Dec. 31, 2012

Income Tax Expense [Abstract]

Income Tax Expense [Text Block]

INCOME TAX EXPENSE



Income Tax Expense
Year Ended December 31	2012			2011			2010
Millions
Current Tax Expense (Benefit)
Federal (a)	—			$1.4			$(23.0)
State (a)	$0.5			(1.6		)	1.3
Total Current Tax Expense (Benefit)	0.5			(0.2		)	(21.7		)
Deferred Tax Expense
Federal (b)	38.1			27.3			61.4
State (b)	(1.7		)	9.5			5.3
Change in Valuation Allowance (c)	2.0			(0.1		)	0.2
Investment Tax Credit Amortization	(0.9		)	(0.9		)	(0.9		)
Total Deferred Tax Expense	37.5			35.8			66.0
Total Income Tax Expense		$38.0			$35.6			$44.3

(a)

For the years ended December 31, 2012 and 2011, the federal and state current tax expense (benefit) was due to NOLs which resulted primarily from the bonus depreciation provision of the Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010. The 2012 and 2011 federal and state NOLs will be carried forward to offset future taxable income. For the year ended December 31, 2010, a federal current tax benefit was recorded as a result of tax planning initiatives and the bonus depreciation provision in the Small Business Jobs Act of 2010. The 2010 federal NOL was partially utilized by carrying it back against prior years’ income with the remainder carried forward to offset future years’ income.

(b)

For the year ended December 31, 2012, the state deferred tax benefit of $1.7 million is due to state renewable tax credits earned which will be carried forward to offset future state income tax expense. The year ended December 31, 2011, included an income tax benefit for the reversal of a $6.2 million deferred tax liability related to a revenue receivable that Minnesota Power agreed to forgo as part of a stipulation and settlement agreement in its 2010 rate case and a benefit of $2.9 million related to the MPUC approval of our request to defer the retail portion of the tax charge taken in 2010 as a result of the PPACA. Included in the year ended December 31, 2010, was a charge of $4.0 million as a result of the PPACA. (See Note 5. Regulatory Matters.)


(c)	For the year ending December 31, 2012, the change in the valuation allowance is due to state renewable tax credits earned in 2012 which are not expected to be utilized within their allowable tax carryforward period.



Reconciliation of Taxes from Federal Statutory
Rate to Total Income Tax Expense
Year Ended December 31	2012			2011			2010
Millions
Income Before Non-Controlling Interest and Income Taxes		$135.1			$129.2			$119.1
Statutory Federal Income Tax Rate	35		%	35		%	35		%
Income Taxes Computed at 35 percent Statutory Federal Rate		$47.3			$45.2			$41.7
Increase (Decrease) in Tax Due to:
State Income Taxes – Net of Federal Income Tax Benefit	1.2			6.0			4.5
Impact of the PPACA	—			—			4.0
Deferred Accounting for Retail Portion of the PPACA	—			(2.9		)	—
2010 Rate Case Stipulation Agreement - Deferred Tax Reversal	—			(6.2		)	—
Regulatory Differences for Utility Plant	(2.2		)	(1.2		)	(2.0		)
Production Tax Credits	(7.6		)	(4.3		)	(1.6		)
Other	(0.7		)	(1.0		)	(2.3		)
Total Income Tax Expense		$38.0			$35.6			$44.3

NOTE 14. INCOME TAX EXPENSE (Continued)

The effective tax rate on income was 28.1 percent for 2012 (27.6 percent for 2011; 37.2 percent for 2010). The 2012 effective rate was primarily impacted by renewable tax credits and by the deduction for AFUDC-Equity (included in Regulatory Differences for Utility Plant, above). The 2011 effective tax rate was primarily impacted by the deduction for AFUDC-Equity, the reversal of a deferred tax liability related to a revenue receivable that Minnesota Power agreed to forgo as part of a stipulation and settlement agreement in its 2010 rate case, renewable tax credits, and the MPUC’s approval of our request to defer the retail portion of the tax charge taken in 2010 as a result of the PPACA. The 2010 effective tax rate was primarily impacted by the PPACA eliminating the tax deduction for expenses that are reimbursed under Medicare Part D, the deduction for AFUDC-Equity, and renewable tax credits.



Deferred Tax Assets and Liabilities
As of December 31	2012			2011
Millions
Deferred Tax Assets
Employee Benefits and Compensation		$120.2			$132.7
Property Related	59.8			56.4
NOL Carryforwards	90.8			61.7
Tax Credit Carryforwards	28.3			12.2
Other	24.6			20.4
Gross Deferred Tax Assets	323.7			283.4
Deferred Tax Asset Valuation Allowance	(2.4		)	(0.4		)
Total Deferred Tax Assets		$321.3			$283.0
Deferred Tax Liabilities
Property Related		$577.1			$482.7
Regulatory Asset for Benefit Obligations	104.3			117.9
Unamortized Investment Tax Credits	11.9			12.8
Partnership Basis Differences	28.6			24.4
Other	30.1			24.0
Total Deferred Tax Liabilities		$752.0			$661.8
Net Deferred Income Taxes		$430.7			$378.8
Recorded as:
Net Current Deferred Tax Liabilities (a)		$6.9			$5.2
Net Long-Term Deferred Tax Liabilities	423.8			373.6
Net Deferred Income Taxes		$430.7			$378.8


(a)	Included in Other Current Liabilities.



NOL and Tax Credit Carryforwards
Year Ended December 31	2012		2011
Millions
Federal NOL carryforwards (a)		$244.1		$162.0
Federal tax credit carryforwards	$16.0		$8.4
State NOL carryforwards (a) (b)	$90.6		$73.1
State tax credit carryforwards (c)	$10.3		$3.8


(a)	Pretax amounts


(b)	Net of $0.4 million valuation allowance.


(c)	Net of $2.0 million valuation allowance.

NOTE 14. INCOME TAX EXPENSE (Continued)

In 2012, we generated federal and various state NOLs and tax credit carryforwards primarily due to the bonus depreciation provisions of the Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010. The 2012 federal NOL will be utilized by carrying it forward to offset future years’ income. The federal NOL and tax credit carryforward periods expire between 2019 and 2032; included in the federal NOL carryforward are charitable contribution carryforwards which expire between 2014 and 2016. We expect to fully utilize the federal NOL, charitable contributions, and federal tax credit carryforwards; therefore no valuation allowance has been recognized as of December 31, 2012.

The state NOLs and tax credits will be carried forward to future tax years. We have established a valuation allowance against certain state NOL and tax credits that we do not expect to utilize before their expiration. The state NOL and tax credit carryforward periods expire between 2024 and 2032; included in the state NOL carryforwards are charitable contribution carryforwards which expire between 2014 and 2016.



Gross Unrecognized Income Tax Benefits	2012			2011			2010
Millions
Balance at January 1		$11.4			$12.3			$9.5
Reductions for Tax Positions Related to the Current Year	—			—			(0.2		)
Additions for Tax Positions Related to Prior Years	—			—			4.4
Reductions for Tax Positions Related to Prior Years	(8.7		)	(0.9		)	—
Reductions for Settlements	—			—			(0.3		)
Reductions for Expired Statute of Limitations	—			—			(1.1		)
Balance as of December 31		$2.7			$11.4			$12.3

Unrecognized tax benefits are the differences between a tax position taken or expected to be taken in a tax return and the benefit recognized and measured pursuant to the “more-likely-than-not” criteria. The unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the annual effective tax rate. In addition, the unrecognized tax benefit balance includes temporary tax positions for which the ultimate deductibility is highly certain but for which there is uncertainty about the timing of such deductibility. A change in the period of deductibility would not affect the effective tax rate but would accelerate the payment of cash to the taxing authority to an earlier period.

The gross unrecognized tax benefits as of December 31, 2012, includes $0.5 million of net unrecognized tax benefits that, if recognized, would affect the annual effective income tax rate. The decrease in the unrecognized tax benefit balance of $8.7 million in 2012 was due to the removal of our uncertain tax position for our tax accounting method change for deductible repairs. During 2012, the IRS issued a directive from its Large Business and International Division to its local examination teams that led to the removal of the repairs uncertain tax position in 2012.

As of December 31, 2012, we had $0.5 million ($1.1 million for 2011 and $0.7 million for 2010) of accrued interest related to unrecognized tax benefits included in our Consolidated Balance Sheet. We classify interest related to unrecognized tax benefits as interest expense and tax-related penalties in operating expenses in our Consolidated Statement of Income. In 2012, we recognized a $0.6 million decrease in interest expense (interest expense of $0.4 million for 2011 and a reduction of interest expense of $0.2 million for 2010). There were no penalties recognized in 2012, 2011 or 2010.

ALLETE and its subsidiaries file a consolidated federal income tax return as well as combined and separate state income tax returns in various jurisdictions. ALLETE is currently under examination by the IRS for the tax years 2005 through 2009. ALLETE is no longer subject to federal or state examination for years before 2005.

During the next 12 months it is reasonably possible the amount of unrecognized tax benefits could be reduced by $2.5 million due to statute expirations and anticipated audit settlements. This amount is primarily due to temporary tax positions.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 136, 172
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 43, 44, 45, 46, 47, 48, 49
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Pension and Other Postretirement Benefit Plans

12 Months Ended

Dec. 31, 2012

Pension and Other Postretirement Benefit Plans [Abstract]

Pension and Other Postretirement Benefit Plans [Text Block]

PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS

We have noncontributory union and non-union defined benefit pension plans covering eligible employees. The plans provide defined benefits based on years of service and final average pay. In 2012, we made total contributions of $7.3 million ($33.8 million in 2011, of which $20.0 million was contributed in shares of ALLETE common stock). We also have a defined contribution pension plan covering substantially all employees. The 2012 plan year employer contributions, which are made through the employee stock ownership plan portion of the RSOP, totaled $7.7 million ($7.3 million for the 2011 plan year.) (See Note 12. Common Stock and Earnings Per Share and Note 16. Employee Stock and Incentive Plans).

In 2006, the non-union defined benefit pension plan was amended to suspend further crediting of service to the plan and to close the plan to new participants. In conjunction with those amendments, contributions were increased to the RSOP. In 2010, the Minnesota Power union defined benefit pension plan was amended to close the plan to new participants beginning February 1, 2011.

We have postretirement health care and life insurance plans covering eligible employees. In 2010, our postretirement health plan was amended to close the plan to employees hired after January 31, 2011. The full eligibility requirement was also amended in 2010, to age 55 with 10 years of participation in the plan. The postretirement health plans are contributory with participant contributions adjusted annually. Postretirement health and life benefits are funded through a combination of Voluntary Employee Benefit Association trusts (VEBAs), established under section 501(c)(9) of the Internal Revenue Code, and an irrevocable grantor trust. In 2012, $1.5 million was contributed to the VEBAs. In 2011, we contributed $10.9 million to the VEBAs. There were no contributions made to the grantor trust in 2012 and 2011.

Management considers various factors when making funding decisions such as regulatory requirements, actuarially determined minimum contribution requirements, and contributions required to avoid benefit restrictions for the pension plans. Contributions are based on estimates and assumptions which are subject to change. We do not expect to make any contributions to the defined benefit pension plan in 2013. In January 2013, we contributed $4.8 million to the defined benefit postretirement health and life plan, of which $2.0 million was contributed to an irrevocable grantor trust and $2.8 million was contributed to the VEBAs. We do not expect to make any additional contributions to the defined benefit postretirement health and life plan in 2013.

Accounting for defined benefit pension and postretirement benefit plans requires that employers recognize on a prospective basis the funded status of their defined benefit pension and other postretirement plans on their Consolidated Balance Sheet and recognize as a component of other comprehensive income, net of tax, the gains or losses and prior service costs or credits that arise during the period but are not recognized as components of net periodic benefit cost.

The defined benefit pension and postretirement health and life benefit costs recognized annually by our regulated companies are expected to be recovered through rates filed with our regulatory jurisdictions. As a result, these amounts that are required to otherwise be recognized in accumulated other comprehensive income have been recognized as a long-term regulatory asset on our Consolidated Balance Sheet, in accordance with the accounting standards for Regulated Operations. The defined benefit pension and postretirement health and life benefit costs associated with our other non-rate base operations are recognized in accumulated other comprehensive income.

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)



Pension Obligation and Funded Status
Year Ended December 31	2012			2011
Millions
Accumulated Benefit Obligation		$598.7			$550.6
Change in Benefit Obligation
Obligation, Beginning of Year		$597.5			$525.6
Service Cost	9.1			7.6
Interest Cost	26.4			27.4
Actuarial Loss	38.5			54.6
Benefits Paid	(30.9		)	(28.6		)
Participant Contributions	11.5			10.9
Obligation, End of Year		$652.1			$597.5
Change in Plan Assets
Fair Value, Beginning of Year		$432.4			$382.0
Actual Return on Plan Assets	38.7			33.2
Employer Contribution	19.9			45.8
Benefits Paid	(30.9		)	(28.6		)
Fair Value, End of Year		$460.1			$432.4
Funded Status, End of Year	$(192.0)			$(165.1)

Net Pension Amounts Recognized in Consolidated Balance Sheet Consist of:
Current Liabilities	$(1.1)			$(1.1)
Non-Current Liabilities	$(190.9)			$(164.0)

The pension costs that are reported as a component within our Consolidated Balance Sheet, reflected in long-term regulatory assets and accumulated other comprehensive income, consist of the following:



Unrecognized Pension Costs
Year Ended December 31	2012		2011
Millions
Net Loss		$286.8		$269.0
Prior Service Cost	0.7		1.1
Total Unrecognized Pension Costs		$287.5		$270.1



Components of Net Periodic Pension Expense
Year Ended December 31	2012			2011			2010
Millions
Service Cost		$9.1			$7.6			$6.2
Interest Cost	26.4			27.4			26.2
Expected Return on Plan Assets	(35.4		)	(34.6		)	(33.7		)
Amortization of Loss	17.5			12.1			6.6
Amortization of Prior Service Cost	0.3			0.3			0.5
Net Pension Expense		$17.9			$12.8			$5.8

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)



Other Changes in Pension Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income and Regulatory Assets
Year Ended December 31	2012			2011
Millions
Net Loss		$35.2			$56.1
Amortization of Prior Service Cost	(0.3		)	(0.3		)
Amortization of Loss	(17.5		)	(12.2		)
Total Recognized in Other Comprehensive Income and Regulatory Assets		$17.4			$43.6



Information for Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets
Year Ended December 31	2012		2011
Millions
Projected Benefit Obligation		$652.1		$597.5
Accumulated Benefit Obligation		$598.7		$550.6
Fair Value of Plan Assets		$460.1		$432.4



Postretirement Health and Life Obligation and Funded Status
Year Ended December 31	2012			2011
Millions
Change in Benefit Obligation
Obligation, Beginning of Year		$210.6			$204.1
Service Cost	4.2			3.8
Interest Cost	9.4			10.8
Actuarial Gain	(43.2		)	(2.9		)
Participant Contributions	2.6			2.5
Plan Amendments	(5.3		)	—
Benefits Paid	(9.5		)	(7.7		)
Obligation, End of Year		$168.8			$210.6
Change in Plan Assets
Fair Value, Beginning of Year		$121.0			$114.7
Actual Return on Plan Assets	14.3			—
Employer Contribution	2.3			11.4
Participant Contributions	2.5			2.5
Benefits Paid	(9.1		)	(7.6		)
Fair Value, End of Year		$131.0			$121.0
Funded Status, End of Year	$(37.8)			$(89.6)

Net Postretirement Health and Life Amounts Recognized in Consolidated Balance Sheet Consist of:
Current Liabilities	$(0.8)			$(0.9)
Non-Current Liabilities	$(37.0)			$(88.7)

According to the accounting standards for retirement benefits, only assets in the VEBAs are treated as plan assets in the above table for the purpose of determining funded status. In addition to the postretirement health and life assets reported in the previous table, we had $22.1 million in irrevocable grantor trusts included in Other Investments on our Consolidated Balance Sheet at December 31, 2012 ($20.3 million at December 31, 2011).

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)

The postretirement health and life costs that are reported as a component within our Consolidated Balance Sheet, reflected in regulatory long-term assets and accumulated other comprehensive income, consist of the following:



Unrecognized Postretirement Health and Life Costs
Year Ended December 31	2012			2011
Millions
Net Loss		$23.5			$78.5
Prior Service Credit	(13.1		)	(9.5		)
Transition Obligation	—			0.1
Total Unrecognized Postretirement Health and Life Costs		$10.4			$69.1



Components of Net Periodic Postretirement Health and Life Expense
Year Ended December 31	2012			2011			2010
Millions
Service Cost		$4.2			$3.8			$4.8
Interest Cost	9.4			10.8			10.9
Expected Return on Plan Assets	(9.9		)	(9.7		)	(9.5		)
Amortization of Prior Service Credit	(1.7		)	(1.7		)	(0.1		)
Amortization of Loss	7.5			8.5			4.8
Amortization of Transition Obligation	0.1			0.1			2.5
Net Postretirement Health and Life Expense		$9.6			$11.8			$13.4



Other Changes in Postretirement Benefit Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income and Regulatory Assets
Year Ended December 31	2012		2011
Millions
Net (Gain) Loss	$(47.5)			$6.9
Prior Service Credit Arising During the Period	(5.3	)	—
Amortization of Prior Service Credit	1.7		1.7
Amortization of Transition Obligation	(0.1	)	(0.1		)
Amortization of Loss	(7.5	)	(8.5		)
Total Recognized in Other Comprehensive Income and Regulatory Assets	$(58.7)		—



Estimated Future Benefit Payments
			Postretirement
	Pension		Health and Life
Millions
2013		$31.2		$7.6
2014		$32.1		$8.2
2015		$33.2		$8.9
2016		$34.4		$9.4
2017		$35.5		$9.7
Years 2018 – 2022		$189.4		$52.0

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)

The pension and postretirement health and life costs recorded in regulatory long-term assets and accumulated other comprehensive income expected to be recognized as a component of net pension and postretirement benefit costs for the year ending December 31, 2013, are as follows:



	Pension		Postretirement Health and Life
Millions
Net Loss		$21.4		$1.6
Prior Service Cost (Credit)	0.3		(2.5		)
Total Pension and Postretirement Health and Life Cost (Credit)		$21.7	$(0.9)



Weighted-Average Assumptions Used to Determine Benefit Obligation
As of December 31	2012	2011
Discount Rate
Pension	4.10%	4.54%
Postretirement Health and Life	4.13%	4.56%
Rate of Compensation Increase	4.3 - 4.6%	4.3 - 4.6%
Health Care Trend Rates
Trend Rate	9.25%	10%
Ultimate Trend Rate	5%	5%
Year Ultimate Trend Rate Effective	2019	2018



Weighted-Average Assumptions Used to Determine Net Periodic Benefit Costs
Year Ended December 31	2012	2011	2010
Discount Rate	4.54 - 4.56%	5.36 - 5.40%	5.81%
Expected Long-Term Return on Plan Assets
Pension	8.25%	8.5%	8.5%
Postretirement Health and Life	6.6 - 8.25%	6.8 - 8.5%	6.8 - 8.5%
Rate of Compensation Increase	4.3 - 4.6%	4.3 - 4.6%	4.3 - 4.6%

In establishing the expected long-term rate of return on plan assets, we determine the long-term historical performance of each asset class, adjust these for current economic conditions, and utilizing the target allocation of our plan assets, forecast the expected long-term rate of return.

The discount rate is computed using a yield curve adjusted for ALLETE’s projected cash flows to match our plan characteristics. The yield curve is determined using high-quality long-term corporate bond rates at the valuation date. We believe the adjusted discount curve used in this comparison does not materially differ in duration and cash flows from our pension obligation.



Sensitivity of a One-Percentage-Point Change in Health Care Trend Rates
	One Percent		One Percent
	Increase		Decrease
Millions
Effect on Total of Postretirement Health and Life Service and Interest Cost		$2.0	$(1.6)
Effect on Postretirement Health and Life Obligation		$18.2	$(15.1)

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)



Actual Plan Asset Allocations
	Pension				Postretirement Health and Life (a)
	2012		2011		2012		2011
Equity Securities	54	%	52	%	56	%	51	%
Debt Securities	28	%	27	%	35	%	39	%
Private Equity	13	%	16	%	9	%	10	%
Real Estate	5	%	5	%	—		—
	100	%	100	%	100	%	100	%


(a)	Includes VEBAs and irrevocable grantor trusts.

There were no shares of ALLETE common stock included in pension plan equity securities at December 31, 2012 ($20.0 million, approximately 0.5 million shares, in 2011).

To achieve strong returns within managed risk, we diversify our asset portfolio to approximate the target allocations in the table below. Equity securities are diversified among domestic companies with large, mid and small market capitalizations, as well as investments in international companies. The majority of debt securities are made up of investment grade bonds.



Plan Asset Target Allocations
			Postretirement
	Pension		Health and Life (a)
Equity Securities	52	%	48	%
Debt Securities	30	%	34	%
Real Estate	9	%	9	%
Private Equity	9	%	9	%
	100	%	100	%


(a)	Includes VEBAs and irrevocable grantor trusts.

Fair Value

Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reported date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. This category includes various U.S. equity securities, public mutual funds, and futures. These instruments are valued using the closing price from the applicable exchange or whose value is quoted and readily traded daily.

Level 2 — Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reported date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts, such as treasury securities with pricing interpolated from recent trades of similar securities, or priced with models using highly observable inputs. This category includes various bonds and non-public funds whose underlying investments may be level 1 or level 2 securities.

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)

Fair Value (Continued)

Level 3 — Significant inputs that are generally less observable from objective sources. The types of assets and liabilities included in Level 3 are those with inputs requiring significant management judgment or estimation, such as the complex and subjective models and forecasts used to determine the fair value. This category includes private equity funds and real estate valued through external appraisal processes. Valuation methodologies incorporate pricing models, discounted cash flow models, and similar techniques which utilize capitalization rates, discount rates, cash flows and other factors.

Pension Fair Value



	Fair Value as of December 31, 2012
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Equity Securities:
U.S. Large-cap (a)		$43.0		$36.0	—			$79.0
U.S. Mid-cap Growth (a)	18.3		15.3		—		33.6
U.S. Small-cap (a)	18.3		15.3		—		33.6
International	50.5		45.9		—		96.4
Debt Securities:
Mutual Funds	72.5		—		—		72.5
Fixed Income	10.4		50.8		—		61.2
Other Types of Investments:
Private Equity Funds	—		—			$58.9	58.9
Real Estate	—		—		24.9		24.9
Total Fair Value of Assets		$213.0		$163.3		$83.8		$460.1

(a)

The underlying investments classified under U.S. Equity Securities consist of money market funds (Level 1) and actively-managed funds (Level 2), which are combined with futures, and settle daily, in a portable alpha program to achieve the returns of the U.S. Equity Securities Large-cap, Mid-cap Growth, and Small-cap funds. Our exposure with respect to these investments includes both the futures and the underlying investments.



Recurring Fair Value Measures
Activity in Level 3	Private Equity Funds			Real Estate
Millions
Balance as of December 31, 2011		$69.0			$21.7
Actual Return on Plan Assets	(9.7		)	3.4
Purchases, sales, and settlements, net	(0.4		)	(0.2		)
Balance as of December 31, 2012		$58.9			$24.9

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)

Fair Value (Continued)



	Fair Value as of December 31, 2011
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Equity Securities:
U.S. Large-cap (a)		$32.1		$37.3	—			$69.4
U.S. Mid-cap Growth (a)	13.5		15.8		—		29.3
U.S. Small-cap (a)	13.1		15.2		—		28.3
International	—		75.1		—		75.1
ALLETE	21.3		—		—		21.3
Debt Securities:
Mutual Funds	72.8		—		—		72.8
Fixed Income	—		45.5		—		45.5
Other Types of Investments:
Private Equity Funds	—		—			$69.0	69.0
Real Estate	—		—		21.7		21.7
Total Fair Value of Assets		$152.8		$188.9		$90.7		$432.4

(a)



Recurring Fair Value Measures
Activity in Level 3	Equity Securities (ARS)			Private Equity Funds			Real Estate
Millions
Balance as of December 31, 2010		$6.7			$50.7			$20.1
Actual Return on Plan Assets	—			30.9			3.5
Purchases, sales, and settlements, net	(6.7		)	(12.6		)	(1.9		)
Balance as of December 31, 2011	—				$69.0			$21.7

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)

Fair Value (Continued)

Postretirement Health and Life Fair Value



	Fair Value as of December 31, 2012
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Equity Securities:
U.S. Large-cap (a)		$16.7	—		—			$16.7
U.S. Mid-cap Growth (a)	13.2		—		—		13.2
U.S. Small-cap (a)	13.3		—		—		13.3
International	30.3		—		—		30.3
Debt Securities:
Mutual Funds	25.5		—		—		25.5
Fixed Income	0.2			$18.3	—		18.5
Other Types of Investments:
Private Equity Funds	—		—			$13.5	13.5
Total Fair Value of Assets		$99.2		$18.3		$13.5		$131.0


(a)	The underlying investments classified under U.S. Equity Securities consist of mutual funds (Level 1).



Recurring Fair Value Measures
Activity in Level 3	Private Equity Funds
Millions
Balance as of December 31, 2011		$14.0
Actual Return on Plan Assets	0.2
Purchases, sales, and settlements, net	(0.7		)
Balance as of December 31, 2012		$13.5



	Fair Value as of December 31, 2011
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Equity Securities:
U.S. Large-cap (a)		$15.9	—		—			$15.9
U.S. Mid-cap Growth (a)	11.5		—		—		11.5
U.S. Small-cap (a)	11.2		—		—		11.2
International	25.1		—		—		25.1
Debt Securities:
Mutual Funds	24.1		—		—		24.1
Fixed Income	0.3			$18.9	—		19.2
Other Types of Investments:
Private Equity Funds	—		—			$14.0	14.0
Total Fair Value of Assets		$88.1		$18.9		$14.0		$121.0


(a)	The underlying investments classified under U.S. Equity Securities consist of mutual funds (Level 1).

NOTE 15. PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Continued)

Fair Value (Continued)



Recurring Fair Value Measures
Activity in Level 3	Private Equity Funds
Millions
Balance as of December 31, 2010		$12.4
Actual Return on Plan Assets	1.1
Purchases, sales, and settlements, net	0.5
Balance as of December 31, 2011		$14.0

Accounting and disclosure requirements for the Medicare Prescription Drug, Improvement and Modernization Act of 2003 (Act) provide guidance for employers that sponsor postretirement health care plans that provide prescription drug benefits. We provide a fully insured postretirement health benefit, including a prescription drug benefit, which qualifies us for a federal subsidy under the Act. The federal subsidy is reflected in the premiums charged to us by the insurance company.

- Definition

The entire disclosure for pension and other postretirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-URI http://asc.fasb.org/topic&trid=2235017

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Implementation Guide (Q and A)
-Number FAS88
-Paragraph 63
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 03-2
-Paragraph 8
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph q
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-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph h
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 8
-Subparagraph m
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-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5, 6, 7, 8
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-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 7, 21, 22
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-Name FASB Staff Position (FSP)
-Number FAS106-2
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-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 30
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+ Details

Employee Stock and Incentive Plans

12 Months Ended

Dec. 31, 2012

Employee Stock and Incentive Plans [Abstract]

Employee Stock and Incentive Plans [Text Block]

EMPLOYEE STOCK AND INCENTIVE PLANS

Employee Stock Ownership Plan. We sponsor a leveraged ESOP within the RSOP. Eligible employees may contribute to the RSOP plan as of their date of hire. In 1990, the ESOP issued a $75.0 million note (term not to exceed 25 years at 10.25 percent) to use as consideration for 2.8 million shares (1.9 million shares adjusted for stock splits) of our newly issued common stock. The note was refinanced in 2006 at 6 percent. We make annual contributions to the ESOP equal to the ESOP’s debt service less available dividends received by the ESOP. The majority of dividends received by the ESOP are used to pay debt service, with the balance distributed to participants. The ESOP shares were initially pledged as collateral for the debt. As the debt is repaid, shares are released from collateral and allocated to participants based on the proportion of debt service paid in the year. As shares are released from collateral, we report compensation expense equal to the current market price of the shares less dividends on allocated shares. Dividends on allocated ESOP shares are recorded as a reduction of retained earnings; available dividends on unallocated ESOP shares are recorded as a reduction of debt and accrued interest. ESOP compensation expense was $7.7 million in 2012 ($7.4 million in 2011; $7.1 million in 2010).

According to the accounting standards for stock compensation, unallocated shares of ALLETE common stock currently held and purchased by the ESOP will be treated as unearned ESOP shares and not considered outstanding for earnings per share computations. ESOP shares are included in earnings per share computations after they are allocated to participants.



Year Ended December 31	2012		2011		2010
Millions
ESOP Shares
Allocated	2.2		2.2		2.2
Unallocated	0.7		1.0		1.3
Total	2.9		3.2		3.5
Fair Value of Unallocated Shares		$28.7		$42.0		$48.4

Stock-Based Compensation. Stock Incentive Plan. Under our Executive Long-Term Incentive Compensation Plan (Executive Plan), share-based awards may be issued to key employees through a broad range of methods, including non-qualified and incentive stock options, performance shares, performance units, restricted stock, stock appreciation rights and other awards. There are 1.2 million shares of common stock reserved for issuance under the Executive Plan, with 0.6 million of these shares available for issuance as of December 31, 2012.

We had a Director Long-Term Stock Incentive Plan (Director Plan) which expired on January 1, 2006. No grants have been made since 2003 under the Director Plan. The 1,293 remaining options outstanding at December 31, 2011, were exercised during 2012. There were no options outstanding under the Director Plan at December 31, 2012.

NOTE 16. EMPLOYEE STOCK AND INCENTIVE PLANS (Continued)

We currently have the following types of share-based awards outstanding:

Non-Qualified Stock Options. These options allow for the purchase of shares of common stock at a price equal to the market value of our common stock at the date of grant. Options become exercisable beginning one year after the grant date, with one-third vesting each year over three years. Options may be exercised up to ten years following the date of grant. In the case of qualified retirement, death or disability, options vest immediately and the period over which the options can be exercised is three years. Employees have up to three months to exercise vested options upon voluntary termination or involuntary termination without cause. All options are canceled upon termination for cause. All options vest immediately upon retirement, death, disability or a change of control, as defined in the award agreement. We determine the fair value of options using the Black-Scholes option-pricing model. The estimated fair value of options, including the effect of estimated forfeitures, is recognized as expense on the straight-line basis over the options’ vesting periods, or the accelerated vesting period if the employee is retirement eligible. Stock options have not been granted under our Executive Plan since 2008.

The risk-free interest rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the grant date. Expected volatility is estimated based on the historic volatility of our stock and the stock of our peer group companies. We utilize historical option exercise and employee pre-vesting termination data to estimate the option life. The dividend growth rate is based upon historical growth rates in our dividends.

Performance Shares. Under the performance share awards plan, the number of shares earned is contingent upon attaining specific market goals over a three-year performance period. Market goals are measured by total shareholder return relative to a group of peer companies. In the case of qualified retirement, death or disability during a performance period, a pro rata portion of the award will be earned at the conclusion of the performance period based on the market goals achieved. In the case of termination of employment for any reason other than qualified retirement, death or disability, no award will be earned. If there is a change in control, a pro rata portion of the award will be paid based on the greater of actual performance up to the date of the change in control or target performance. The fair value of these awards is determined by the probability of meeting the total shareholder return goals. Compensation cost is recognized over the three-year performance period based on our estimate of the number of shares which will be earned by the award recipients.

Restricted Stock Units. Under the restricted stock units plan, shares for retirement eligible participants vest monthly over a three-year period. For non-retirement eligible participants, shares vest at the end of the three-year period. In the case of qualified retirement, death or disability, a pro rata portion of the award will be earned. In the case of termination of employment for any reason other than qualified retirement, death or disability, no award will be earned. If there is a change in control, a pro rata portion of the award will be earned. The fair value of these awards is equal to the grant date fair value. Compensation cost is recognized over the three-year vesting period based on our estimate of the number of shares which will be earned by the award recipients.

Employee Stock Purchase Plan (ESPP). Under our ESPP, eligible employees may purchase ALLETE common stock at a 5 percent discount from the market price. Because the discount is not greater than 5 percent, we are not required to apply fair value accounting to these awards.

RSOP. The RSOP is a contributory defined contribution plan subject to the provisions of the Employee Retirement Income Security Act of 1974, as amended, and qualifies as an employee stock ownership plan and profit sharing plan. The RSOP provides eligible employees an opportunity to save for retirement.

The following share-based compensation expense amounts were recognized in our Consolidated Statement of Income for the periods presented.



Share-Based Compensation Expense
Year Ended December 31	2012		2011		2010
Millions
Stock Options	—		—			$0.1
Performance Shares		$1.4		$1.1	1.5
Restricted Stock Units	0.7		0.5		0.6
Total Share-Based Compensation Expense		$2.1		$1.6		$2.2
Income Tax Benefit		$0.9		$0.7		$0.9

NOTE 16. EMPLOYEE STOCK AND INCENTIVE PLANS (Continued)

There were no capitalized stock-based compensation costs at December 31, 2012, 2011, or 2010.

As of December 31, 2012, the total unrecognized compensation cost for the performance share awards and restricted stock units not yet recognized in our Consolidated Statements of Income was $1.3 million and $0.6 million, respectively. These amounts are expected to be recognized over a weighted-average period of 1.7 years for performance share awards and 1.7 years for restricted stock units.

Non-Qualified Stock Options. The following table presents information regarding our outstanding stock options as of December 31, 2012.



	2012			2011			2010
	Number of Options	Weighted-Average Exercise Price		Number of Options	Weighted-Average Exercise Price		Number of Options	Weighted-Average Exercise Price
Outstanding as of January 1,	460,234		$41.68	560,887		$40.69	646,235		$40.05
Granted (a)	—	—		—	—		—	—
Exercised	49,075		$35.84	80,798		$34.25	40,769		$27.76
Forfeited	15,481		$44.86	19,855		$43.96	44,579		$43.16
Outstanding as of December 31,	395,678		$42.28	460,234		$41.68	560,887		$40.69
Exercisable as of December 31,	395,678		$41.71	460,234		$41.59	523,491		$39.76


(a)	Stock options have not been granted since 2008. The weighted-average grant-date intrinsic value of options granted in 2008 was $6.18.

Cash received from non-qualified stock options exercised was less than $0.1 million in 2012. The intrinsic value of a stock award is the amount by which the fair value of the underlying stock exceeds the exercise price of the award. The total intrinsic value of options exercised was $0.3 million during 2012 ($0.5 million in 2011; $0.3 million in 2010).



	Range of Exercise Price
As of December 31, 2012	$23.79 to $26.91		$37.76 to $41.35		$44.15 to $48.65
Options Outstanding and Exercisable:
Number Outstanding and Exercisable	1,340		236,052		158,286
Weighted Average Remaining Contractual Life (Years)	0.1		3.5		3.6
Weighted Average Exercise Price		$23.79		$39.64		$46.38

Performance Shares. The following table presents information regarding our non-vested performance shares as of December 31, 2012.



	2012				2011				2010
	Number of Shares		Weighted- Average Grant Date Fair Value		Number of Shares		Weighted- Average Grant Date Fair Value		Number of Shares		Weighted- Average Grant Date Fair Value
Non-vested as of January 1,	128,333			$36.54	122,489			$38.15	121,825			$41.96
Granted (a)	38,764			$44.70	39,312			$41.00	49,302			$35.44
Awarded	(41,009	)		$34.25	(32,368	)		$48.10	—		—
Unearned Grant Award	(17,575	)		$34.25	—		—		(22,909	)		$54.50
Forfeited	(614	)		$34.49	(1,100	)		$34.35	(25,729	)		$36.45
Non-vested as of December 31,	107,899			$40.73	128,333			$36.54	122,489			$38.15

(a) Shares granted includes accrued dividends.

NOTE 16. EMPLOYEE STOCK AND INCENTIVE PLANS (Continued)

There were 33,525 and 41,332 performance shares granted in January 2012 and 2013, for the three-year performance periods ending in 2014 and 2015, respectively. The ultimate issuance is contingent upon the attainment of certain future market goals of ALLETE during the performance periods. The grant date fair value of the performance shares granted was $1.5 million and $2.2 million, respectively.

There were 41,009 and 18,605 performance shares awarded in February 2012 and 2013, for the three-year performance periods ending in 2011 and 2012, respectively. The grant date fair value of the shares awarded was $1.4 million and $0.7 million, respectively.

Restricted Stock Units. The following table presents information regarding our available restricted stock units as of December 31, 2012.



	2012				2011				2010
	Number of Shares		Weighted- Average Grant Date Fair Value		Number of Shares		Weighted- Average Grant Date Fair Value		Number of Shares		Weighted- Average Grant Date Fair Value
Available as of January 1,	63,464			$32.57	43,803			$30.61	28,983			$29.41
Granted (a)	18,162			$40.83	20,136			$36.74	26,589			$31.83
Awarded	(24,707	)		$29.43	(215	)		$30.30	(3,091	)		$29.75
Forfeited	(504	)		$31.80	(260	)		$29.41	(8,678	)		$30.62
Available as of December 31,	56,415			$36.61	63,464			$32.57	43,803			$30.61

(a) Shares granted includes accrued dividends.

There were 16,355 and 19,193 restricted stock units granted in January 2012 and 2013, for the vesting periods ending in 2014 and 2015, respectively. The grant date fair value of the restricted stock units granted was $0.7 million and $0.8 million, respectively.

There were 24,707 restricted stock units awarded in 2012. The grant date fair value of the shares awarded was $0.7 million.

There were 20,939 restricted stock units awarded in February 2013. The grant date fair value of the shares awarded was $0.7 million.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 50
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6406099&loc=d3e25284-112666

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5444-113901

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph 64, 65, A240
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 93-6
-Paragraph 53
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2012

Quarterly Financial Data (Unaudited) [Abstract]

Quarterly Financial Data (Unaudited) [Text Block]

QUARTERLY FINANCIAL DATA (UNAUDITED)

Information for any one quarterly period is not necessarily indicative of the results which may be expected for the year.



Quarter Ended	Mar. 31		Jun. 30		Sept. 30		Dec. 31
Millions Except Earnings Per Share
2012
Operating Revenue		$240.0		$216.4		$248.8		$256.0
Operating Income		$38.4		$23.3		$45.6		$47.9
Net Income Attributable to ALLETE		$24.4		$14.4		$29.4		$28.9
Earnings Per Share of Common Stock
Basic		$0.66		$0.39		$0.78		$0.76
Diluted		$0.66		$0.39		$0.78		$0.75
2011
Operating Revenue		$242.2		$219.9		$226.9		$239.2
Operating Income		$50.8		$26.1		$38.9		$34.2
Net Income Attributable to ALLETE		$37.2		$17.0		$20.5		$19.1
Earnings Per Share of Common Stock
Basic		$1.07		$0.49		$0.57		$0.53
Diluted		$1.07		$0.48		$0.57		$0.53

- Definition

The entire disclosure for the quarterly financial data in the annual financial statements. The disclosure may include a tabular presentation of financial information for each fiscal quarter for the current and previous year, including revenues, gross profit, income or loss before extraordinary items and earnings per share data. It also includes an indication if the information in the note is unaudited, comments on the aggregate effect of year-end adjustments, and an explanation of matters or transactions that affect comparability or are pertinent to an understanding of the information furnished.

+ References + Details

Schedule II

12 Months Ended

Dec. 31, 2012

Schedule II [Abstract]

Valuation and Qualifying Accounts and Reserves [Text Block]

Schedule II

ALLETE

Valuation and Qualifying Accounts and Reserves



	Balance at Beginning of Period		Additions			Deductions from Reserves (a)		Balance at End of Period
	Balance at Beginning of Period		Charged to Income		Other Charges	Deductions from Reserves (a)		Balance at End of Period
Millions
Reserve Deducted from Related Assets
Reserve For Uncollectible Accounts
2010 Trade Accounts Receivable		$0.9		$1.1	—		$1.1		$0.9
Finance Receivables – Long-Term		$0.4		$0.8	—		$0.4		$0.8
2011 Trade Accounts Receivable		$0.9		$1.3	—		$1.3		$0.9
Finance Receivables – Long-Term		$0.8		$0.1	—		$0.3		$0.6
2012 Trade Accounts Receivable		$0.9		$1.0	—		$0.9		$1.0
Finance Receivables – Long-Term		$0.6	—		—	—			$0.6
Deferred Asset Valuation Allowance
2010 Deferred Tax Assets		$0.3	$0.2		—	—			$0.5
2011 Deferred Tax Assets		$0.5	$(0.1)		—	—			$0.4
2012 Deferred Tax Assets		$0.4		$2.0	—	—			$2.4


(a)	Includes uncollectible accounts written off.

Operations and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2012
Operations and Significant Accounting Policies [Abstract]
Financial Statement Preparation [Policy Text Block]	Financial Statement Preparation. References in this report to “we,” “us,” and “our” are to ALLETE and its subsidiaries, collectively. We prepare our financial statements in conformity with accounting principles generally accepted in the United States of America. These principles require management to make informed judgments, best estimates, and assumptions that affect the reported amounts of assets, liabilities, revenue, and expenses. Actual results could differ from those estimates.
Subsequent Events [Policy Text Block]	Subsequent Events. The Company performed an evaluation of subsequent events for potential recognition and disclosure through the time of the financial statements issuance.
Principles of Consolidation [Policy Text Block]	Principles of Consolidation. Our consolidated financial statements include the accounts of ALLETE and all of our majority-owned subsidiary companies. All material intercompany balances and transactions have been eliminated in consolidation.
Business Segments [Policy Text Block]	Business Segments. Our Regulated Operations and Investments and Other segments were determined in accordance with the guidance on segment reporting. Segmentation is based on the manner in which we operate, assess, and allocate resources to the business. We measure performance of our operations through budgeting and monitoring of contributions to consolidated net income by each business segment.
Land Inventory [Policy Text Block]	Land inventories are accounted for in accordance with the accounting standards for property, plant and equipment, and are included in Other Investments on our Consolidated Balance Sheet. Real estate costs include the cost of land acquired, subsequent development costs and costs of improvements, capitalized development period interest, real estate taxes and payroll costs of certain employees devoted directly to the development effort. These real estate costs incurred are capitalized to the cost of real estate parcels based upon the relative sales value of parcels within each development project in accordance with the accounting standards for real estate. The cost of real estate sold includes the actual costs incurred and the estimate of future completion costs allocated to the real estate sold based upon the relative sales value method. Whenever events or circumstances indicate that the carrying value of the real estate may not be recoverable, impairments are recorded and the related assets are adjusted to their estimated fair value.
Cash and Cash Equivalents [Policy Text Block]	Cash and Cash Equivalents. We consider all investments purchased with original maturities of three months or less to be cash equivalents.
Accounts Receivable [Policy Text Block]	Accounts Receivable. Accounts receivable are reported on the balance sheet net of an allowance for doubtful accounts. The allowance is based on our evaluation of the receivable portfolio under current conditions, overall portfolio quality, review of specific problems and such other factors that, in our judgment, deserve recognition in estimating losses.
Long-Term Finance Receivables [Policy Text Block]	Long-Term Finance Receivables. Long-term finance receivables relating to our real estate operations are collateralized by property sold, accrue interest at market-based rates and are net of an allowance for doubtful accounts. We assess delinquent finance receivables by comparing the balance of such receivables to the estimated fair value of the collateralized property. If the fair value of the property is less than the finance receivable, we record a reserve for the difference. We estimate fair value based on recent property tax assessed values or current appraisals.
Available-for-Sale Securities [Policy Text Block]	Available-for-Sale Securities. Available-for-sale securities are recorded at fair value with unrealized gains and losses included in accumulated other comprehensive income (loss), net of tax. Unrealized losses that are other than temporary are recognized in earnings. We use the specific identification method as the basis for determining the cost of securities sold. Our policy is to review available-for-sale securities for other than temporary impairment on a quarterly basis by assessing such factors as the share price trends and the impact of overall market conditions.
Inventories [Policy Text Block]	Inventories. Inventories are stated at the lower of cost or market. Amounts removed from inventory are recorded on an average cost basis.
Property, Plant and Equipment [Policy Text Block]	Property, Plant and Equipment. Property, plant and equipment are recorded at original cost and are reported on the balance sheet net of accumulated depreciation. Expenditures for additions, significant replacements, improvements and major plant overhauls are capitalized; maintenance and repair costs are expensed as incurred. Gains or losses on non-rate base property, plant and equipment are recognized when they are retired or otherwise disposed. When regulated utility property, plant and equipment are retired or otherwise disposed, no gain or loss is recognized in accordance with the accounting standards for Regulated Operations. Our Regulated Operations capitalize AFUDC, which includes both an interest and equity component. AFUDC represents the cost of both debt and equity funds used to finance utility plant additions during construction periods. AFUDC amounts capitalized are included in rate base and are recovered from customers as the related property is depreciated. The MPUC has approved cost recovery for several large capital projects recently, at which time the recognition of AFUDC ceases. Depreciation is computed using the straight-line method over the estimated useful lives of the various classes of assets.
Impairment of Long-Lived Assets [Policy Text Block]	Impairment of Long-Lived Assets. We review our long-lived assets, which include the real estate assets of ALLETE Properties, for indicators of impairment in accordance with the accounting standards for property, plant and equipment on a quarterly basis. In the event that projected future undiscounted cash flows are not adequate to recover the carrying value of an asset, impairment is indicated and may require a write down to the asset’s fair value. Fair value is determined based on best available evidence including comparable sales, current appraised values, property tax assessed values, and discounted cash flow analysis. If fair value is less than cost, the carrying value of our investments is reduced and an impairment charge is recorded in the current period. In accordance with the accounting standards for property, plant and equipment, if indicators of impairment exist, we test our real estate assets for recoverability by comparing the carrying amount of the asset to the undiscounted future net cash flows expected to be generated by the asset. Cash flows are assessed at the lowest level of identifiable cash flows, which may be by each land parcel, combining various parcels into bulk sales, or other combinations thereof. Our consideration of possible impairment for our real estate assets requires us to make estimates of future cash flows on an undiscounted basis. The undiscounted future net cash flows are impacted by trends and factors known to us at the time they are calculated and our expectations related to: management’s best estimate of future sales prices; holding period and timing of sales; method of disposition; and future expenditures necessary to develop and maintain the operations, including community development district assessments, property taxes and normal operation and maintenance costs. These estimates and expectations are specific to each land parcel or various bulk sales, and may vary among each land parcel or bulk sale. If the excess of undiscounted cash flows over the carrying value of a property is small, there is a greater risk of future impairment in the event of such changes and any resulting impairment charges could be material.
Derivatives [Policy Text Block]	Derivatives. ALLETE is exposed to certain risks relating to its business operations that can be managed through the use of derivative instruments. ALLETE may enter into derivative instruments to manage interest rate risk related to certain variable-rate borrowings. Cash flows from derivative activities are presented in the same category as the item being hedged on the Consolidated Statement of Cash Flows. Amounts recorded in other comprehensive income related to cash flow hedges will be recognized in earnings when the hedged transactions occur or when it is probable that the hedged transactions will not occur. Gains or losses on interest rate hedging transactions are reflected as a component of interest expense on the Consolidated Statement of Income.
Accounting for Stock-Based Compensation [Policy Text Block]	Accounting for Stock-Based Compensation. We apply the fair value recognition guidance for share-based payments. Under this guidance, we recognize stock-based compensation expense for all share-based payments granted, net of an estimated forfeiture rate.
Environmental Liabilities [Policy Text Block]	Environmental Liabilities. We review environmental matters for disclosure on a quarterly basis. Accruals for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated, based on current law and existing technologies. These accruals are adjusted periodically as assessment and remediation efforts progress or as additional technical or legal information becomes available. Accruals for environmental liabilities are included in the balance sheet at undiscounted amounts and exclude claims for recoveries from insurance or other third parties. Costs related to environmental contamination treatment and cleanup are charged to operating expense unless recoverable in rates from customers.
Revenue Recognition [Policy Text Block]	Revenue Recognition. Regulated utility rates are under the jurisdiction of Minnesota, Wisconsin and federal regulatory authorities. Customers are billed on a cycle basis. Revenue is accrued for service provided but not billed. Regulated utility electric rates include adjustment clauses that: (1) bill or credit customers for fuel and purchased energy costs above or below the base levels in rate schedules; (2) bill retail customers for the recovery of conservation improvement program expenditures not collected in base rates; and (3) bill customers for the recovery of certain transmission and renewable energy expenditures. Fuel and purchased power expense is deferred to match the period in which the revenue for fuel and purchased power expense is collected from customers pursuant to the fuel adjustment clause. BNI recognizes revenue when coal is delivered. Minnesota Power participates in MISO. MISO transactions are accounted for on a net hourly basis in each of the day-ahead and real-time markets. Minnesota Power records net sales in Operating Revenue and net purchases in Fuel and Purchased Power Expense on our Consolidated Statement of Income. The revenues and charges from MISO related to serving retail and municipal electric customers are recorded on a net basis as Fuel and Purchased Power Expense. Full profit recognition is recorded on sales upon closing, provided that cash collections are at least 20 percent of the contract price and the other requirements under the guidance for sales of real estate are met. In certain cases, where there are obligations to perform significant development activities after the date of sale, we recognize profit on a percentage-of-completion basis. From time to time, certain contracts with customers allow us to receive participation revenue from land sales to third parties if various formula-based criteria are achieved. In certain cases, we pay fees or construct improvements to mitigate offsite traffic impacts. In return, we receive traffic impact fee credits as a result of some of these expenditures. We recognize revenue from the sale of traffic impact fee credits when payment is received.
Unamortized Discount and Premium on Debt [Policy Text Block]	Unamortized Discount and Premium on Debt. Discount and premium on debt are deferred and amortized over the terms of the related debt instruments using the straight-line method which approximates the effective interest method.
Income Taxes [Policy Text Block]	Income Taxes. ALLETE and its subsidiaries file a consolidated federal income tax return and combined and separate state income tax returns. We account for income taxes using the liability method in accordance with the accounting standards for income taxes. Under the liability method, deferred income tax assets and liabilities are established for all temporary differences in the book and tax basis of assets and liabilities, based upon enacted tax laws and rates applicable to the periods in which the taxes become payable. Due to the effects of regulation on Minnesota Power and SWL&P, certain adjustments made to deferred income taxes are, in turn, recorded as regulatory assets or liabilities. Federal investment tax credits have been recorded as deferred credits and are being amortized to income tax expense over the service lives of the related property. In accordance with the accounting standards for uncertainty in income taxes, we are required to recognize in our financial statements the largest tax benefit of a tax position that is “more-likely-than-not” to be sustained on audit, based solely on the technical merits of the position as of the reporting date. The term “more-likely-than-not” means more than 50 percent likely.
Excise Taxes [Policy Text Block]	Excise Taxes. We collect excise taxes from our customers levied by government entities. These taxes are stated separately on the billing to the customer and recorded as a liability to be remitted to the government entity. We account for the collection and payment of these taxes on a net basis.
Asset Retirement Obligations [Policy Text Block]	Asset Retirement Obligations. We recognize, at fair value, obligations associated with the retirement of certain tangible, long-lived assets that result from the acquisition, construction or development and/or normal operation of the asset.
Regulatory Assets and Liabilities [Policy Text Block]	Regulatory Assets and Liabilities. Our regulated utility operations are subject to the accounting guidance for Regulated Operations. We capitalize incurred costs which are probable of recovery in future utility rates as regulatory assets. Regulatory liabilities represent amounts expected to be refunded or credited to customers in rates. No regulatory assets or liabilities are currently earning a return.
Fair Value Transfers [Policy Text Block]	The Company’s policy is to recognize transfers in and transfers out as of the actual date of the event or change in circumstances that caused the transfer.
Pension and Other Postretirement Benefit Plans [Policy Text Block]	Accounting for defined benefit pension and postretirement benefit plans requires that employers recognize on a prospective basis the funded status of their defined benefit pension and other postretirement plans on their Consolidated Balance Sheet and recognize as a component of other comprehensive income, net of tax, the gains or losses and prior service costs or credits that arise during the period but are not recognized as components of net periodic benefit cost. The defined benefit pension and postretirement health and life benefit costs recognized annually by our regulated companies are expected to be recovered through rates filed with our regulatory jurisdictions. As a result, these amounts that are required to otherwise be recognized in accumulated other comprehensive income have been recognized as a long-term regulatory asset on our Consolidated Balance Sheet, in accordance with the accounting standards for Regulated Operations. The defined benefit pension and postretirement health and life benefit costs associated with our other non-rate base operations are recognized in accumulated other comprehensive income.
Employee Stock Ownership Plan (ESOP) [Policy Text Block]	We make annual contributions to the ESOP equal to the ESOP’s debt service less available dividends received by the ESOP. The majority of dividends received by the ESOP are used to pay debt service, with the balance distributed to participants. The ESOP shares were initially pledged as collateral for the debt. As the debt is repaid, shares are released from collateral and allocated to participants based on the proportion of debt service paid in the year. As shares are released from collateral, we report compensation expense equal to the current market price of the shares less dividends on allocated shares. Dividends on allocated ESOP shares are recorded as a reduction of retained earnings; available dividends on unallocated ESOP shares are recorded as a reduction of debt and accrued interest. According to the accounting standards for stock compensation, unallocated shares of ALLETE common stock currently held and purchased by the ESOP will be treated as unearned ESOP shares and not considered outstanding for earnings per share computations. ESOP shares are included in earnings per share computations after they are allocated to participants.

Operations and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Operations and Significant Accounting Policies [Abstract]

Supplemental Statement of Cash Flow Information [Table Text Block]

Supplemental Statement of Cash Flow Information



Consolidated Statement of Cash Flows
Year Ended December 31	2012		2011		2010
Millions
Cash Paid During the Period for Interest – Net of Amounts Capitalized		$42.7		$43.2		$35.7
Cash Received During the Period for Income Taxes (a)	—		$(11.4)		$(54.2)
Noncash Investing and Financing Activities
Increase in Accounts Payable for Capital Additions to Property, Plant and Equipment		$20.2		$5.9	$7.5
Capitalized Asset Retirement Costs		$17.1		$0.3		$2.8
AFUDC – Equity		$5.1		$2.5		$4.2
ALLETE Common Stock Contributed to the Pension Plan	—		$(20.0)		—


(a)	Due to bonus depreciation provisions in 2009 and 2010 federal legislation, NOLs were generated which resulted in little or no estimated tax payments, and refunds were received from NOL carrybacks against prior years’ taxable income.

Accounts Receivable [Table Text Block]



Accounts Receivable
As of December 31	2012		2011
Millions
Trade Accounts Receivable
Billed		$70.4		$63.7
Unbilled	17.4		15.6
Less: Allowance for Doubtful Accounts	1.0		0.9
Total Trade Accounts Receivable	86.8		78.4
Income Taxes Receivable	2.2		1.3
Total Accounts Receivable - Net		$89.0		$79.7

Inventories [Table Text Block]



Inventories
As of December 31	2012		2011
Millions
Fuel		$28.0		$28.6
Materials and Supplies	41.8		40.5
Total Inventories		$69.8		$69.1

Prepayments and Other Current Assets [Table Text Block]



Prepayments and Other Current Assets
As of December 31	2012		2011
Millions
Deferred Fuel Adjustment Clause		$22.5		$17.5
Other	11.1		9.6
Total Prepayments and Other Current Assets		$33.6		$27.1

Other Liabilities [Table Text Block]



Other Current Liabilities
As of December 31	2012		2011
Millions
Customer Deposits (a)		$28.8		$16.3
Other	33.8		29.3
Total Other Current Liabilities		$62.6		$45.6


(a)	Customer deposits were higher in 2012 primarily due to customer security deposits for capital expenditures relating to a transmission project.



Other Non-Current Liabilities
As of December 31	2012		2011
Millions
Asset Retirement Obligation		$77.9		$57.0
Other	45.4		48.1
Total Other Non-Current Liabilities		$123.3		$105.1

Business Segments (Tables)

12 Months Ended

Dec. 31, 2012

Business Segments [Abstract]

Business Segments [Table Text Block]



	Consolidated			Regulated Operations			Investments and Other
Millions
2011
Operating Revenue		$928.2			$851.9			$76.3
Fuel and Purchased Power Expense	306.6			306.6			—
Operating and Maintenance Expense	381.2			301.5			79.7
Depreciation Expense	90.4			85.4			5.0
Operating Income (Loss)	150.0			158.4			(8.4		)
Interest Expense	(43.6		)	(35.8		)	(7.8		)
Equity Earnings in ATC	18.4			18.4			—
Other Income	4.4			2.6			1.8
Income (Loss) Before Non-Controlling Interest and Income Taxes	129.2			143.6			(14.4		)
Income Tax Expense (Benefit)	35.6			43.2			(7.6		)
Net Income (Loss)	93.6			100.4			(6.8		)
Less: Non-Controlling Interest in Subsidiaries	(0.2		)	—			(0.2		)
Net Income (Loss) Attributable to ALLETE		$93.8			$100.4		$(6.6)
Total Assets		$2,876.0			$2,579.8			$296.2
Capital Additions		$246.8			$228.0			$18.8



	Consolidated			Regulated Operations			Investments and Other
Millions
2010
Operating Revenue		$907.0			$835.5			$71.5
Fuel and Purchased Power Expense	325.1			325.1			—
Operating and Maintenance Expense	365.6			292.3			73.3
Depreciation Expense	80.5			76.1			4.4
Operating Income (Loss)	135.8			142.0			(6.2		)
Interest Expense	(39.2		)	(32.3		)	(6.9		)
Equity Earnings in ATC	17.9			17.9			—
Other Income	4.6			3.8			0.8
Income (Loss) Before Non-Controlling Interest and Income Taxes	119.1			131.4			(12.3		)
Income Tax Expense (Benefit)	44.3			51.6			(7.3		)
Net Income (Loss)	74.8			79.8			(5.0		)
Less: Non-Controlling Interest in Subsidiaries	(0.5		)	—			(0.5		)
Net Income (Loss) Attributable to ALLETE		$75.3			$79.8		$(4.5)
Total Assets		$2,609.1			$2,375.4			$233.7
Capital Additions		$260.0			$256.4			$3.6



	Consolidated			Regulated Operations			Investments and Other
Millions
2012
Operating Revenue		$961.2			$874.4			$86.8
Fuel and Purchased Power Expense	308.7			308.7			—
Operating and Maintenance Expense	397.1			310.0			87.1
Depreciation Expense	100.2			93.9			6.3
Operating Income (Loss)	155.2			161.8			(6.6		)
Interest Expense	(45.5		)	(39.8		)	(5.7		)
Equity Earnings in ATC	19.4			19.4			—
Other Income	6.0			5.1			0.9
Income (Loss) Before Non-Controlling Interest and Income Taxes	135.1			146.5			(11.4		)
Income Tax Expense (Benefit)	38.0			50.4			(12.4		)
Net Income	97.1			96.1			1.0
Less: Non-Controlling Interest in Subsidiaries	—			—			—
Net Income Attributable to ALLETE		$97.1			$96.1			$1.0
Total Assets		$3,253.4			$2,962.4			$291.0
Capital Additions		$432.2			$418.2			$14.0

- Definition

Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

+ References + Details

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2012

Property, Plant and Equipment [Abstract]

Property, Plant, and Equipment [Table Text Block]



Property, Plant and Equipment
As of December 31	2012			2011
Millions
Regulated Utility		$3,232.9			$2,794.8
Construction Work in Progress	151.8			155.0
Accumulated Depreciation	(1,102.8		)	(1,024.6		)
Regulated Utility Plant - Net	2,281.9			1,925.2
Non-Rate Base Energy Operations	118.0			106.4
Construction Work in Progress	4.2			2.3
Accumulated Depreciation	(56.7		)	(51.4		)
Non-Rate Base Energy Operations Plant - Net	65.5			57.3
Other Plant - Net	0.2			0.2
Property, Plant and Equipment - Net		$2,347.6			$1,982.7

Estimated Useful Lives of Property, Plant and Equipment [Table Text Block]



Estimated Useful Lives of Property, Plant and Equipment

Regulated Utility –	Generation	3 to 35 years	Non-Rate Base Operations	3 to 61 years
	Transmission	42 to 61 years	Other Plant	5 to 25 years
	Distribution	14 to 65 years

Asset Retirement Obligation [Table Text Block]



Asset Retirement Obligation
Millions
Obligation as of December 31, 2010		$50.3
Accretion Expense	6.4
Additional Liabilities Incurred in 2011	0.3
Obligation as of December 31, 2011	57.0
Accretion Expense	3.8
Additional Liabilities Incurred in 2012	17.1
Obligation as of December 31, 2012		$77.9

Jointly-Owned Facilities (Tables)

12 Months Ended

Dec. 31, 2012

Jointly-Owned Facilities [Abstract]

Jointly-Owned Facilities [Table Text Block]

Following are our investments in jointly-owned facilities and the related ownership percentages as of December 31, 2012:



Regulated Utility Plant	Plant in Service		Accumulated Depreciation		Construction Work in Progress		% Ownership
Millions
Boswell Unit 4		$413.1		$188.1		$25.0	80
CapX2020	22.8		0.4		25.4		9.3 - 14.7
Total		$435.9		$188.5		$50.4

Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2012

Regulatory Matters [Abstract]

Regulatory Assets and Liabilities [Table Text Block]



Regulatory Assets and Liabilities
As of December 31	2012		2011
Millions
Current Regulatory Assets (a)
Deferred Fuel		$22.5		$17.5
Total Current Regulatory Assets	22.5		17.5
Non-Current Regulatory Assets
Future Benefit Obligations Under
Defined Benefit Pension and Other Postretirement Plans	260.7		292.8
Income Taxes	36.0		28.6
Asset Retirement Obligation	12.1		9.8
Cost Recovery Riders (b)	18.5		0.7
PPACA Income Tax Deferral	5.0		5.0
Conservation Improvement Program	4.3		4.6
Other	3.7		4.4
Total Non-Current Regulatory Assets	340.3		345.9

Total Regulatory Assets		$362.8		$363.4

Non-Current Regulatory Liabilities
Income Taxes		$19.5		$21.9
Plant Removal Obligations	18.1		15.0
Wholesale and Retail Contra AFUDC	15.5		1.5
Other	7.0		5.1
Total Non-Current Regulatory Liabilities		$60.1		$43.5


(a)	Current regulatory assets are included in prepayments and other on our Consolidated Balance Sheet.


(b)	The increase in cost recovery rider regulatory assets in 2012 is primarily due to revenues related to our Bison Wind Energy Center.

Investment in ATC (Tables)

12 Months Ended

Dec. 31, 2012

Investment in ATC [Abstract]

ALLETE's Interest in ATC [Table Text Block]



ALLETE’s Interest in ATC
Year Ended December 31	2012			2011
Millions
Equity Investment Beginning Balance		$98.9			$93.3
Cash Investments	4.7			2.0
Equity in ATC Earnings	19.4			18.4
Distributed ATC Earnings	(15.7		)	(14.8		)
Equity Investment Ending Balance		$107.3			$98.9

ATC Summarized Financial Data [Table Text Block]



ATC Summarized Financial Data
Balance Sheet Data
As of December 31	2012		2011
Millions
Current Assets		$63.1		$58.7
Non-Current Assets	3,274.7		3,053.7
Total Assets		$3,337.8		$3,112.4
Current Liabilities		$251.5		$298.5
Long-Term Debt	1,550.0		1,400.0
Other Non-Current Liabilities	95.8		82.6
Members’ Equity	1,440.5		1,331.3
Total Liabilities and Members’ Equity		$3,337.8		$3,112.4



Income Statement Data
Year Ended December 31	2012		2011		2010
Millions
Revenue		$603.2		$567.2		$556.7
Operating Expense	281.0		261.6		251.1
Other Expense	84.8		81.7		85.9
Net Income		$237.4		$223.9		$219.7
ALLETE’s Equity in Net Income		$19.4		$18.4		$17.9

Investments (Tables)

12 Months Ended

Dec. 31, 2012

Investments [Abstract]

Investments and ALLETE Properties [Table Text Block]



Investments
As of December 31	2012		2011
Millions
ALLETE Properties		$91.1		$91.3
Available-for-sale Securities	26.8		24.7
Other	25.6		16.3
Total Investments		$143.5		$132.3

NOTE 7. INVESTMENTS (Continued)



ALLETE Properties
As of December 31	2012			2011
Millions
Land Inventory Beginning Balance		$86.0			$86.0
Deeds to Collateralized Property	0.5			1.8
Land Impairment	—			(1.7		)
Cost of Sales	(0.2		)	(0.3		)
Capitalized Improvements and Other	0.2			0.2
Land Inventory Ending Balance	86.5			86.0
Long-Term Finance Receivables (net of allowances of $0.6 and $0.6)	1.4			2.0
Other	3.2			3.3
Total Real Estate Assets		$91.1			$91.3

Available-for-sale Securities [Table Text Block]



Available-For-Sale Securities
Millions		Gross Unrealized
As of December 31	Cost	Gain	(Loss)	Fair Value
2012	$27.4	$0.5	$(1.1)	$26.8
2011	$27.3	$0.1	$(2.7)	$24.7
2010	$27.4	$0.2	$(2.4)	$25.2

Available-for-sale Securities [Table Text Block]



	Net	Gross Realized		Net Unrealized Gain (Loss) in Other
Year Ended December 31	Proceeds	Gain	(Loss)	Comprehensive Income
2012	$1.5	—	—	$1.2
2011	$7.8	—	—	$(0.3)
2010	$0.6	—	—	$0.8

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27337-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27198-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27161-111563

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27290-111563

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 19, 20, 21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 17
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 03-1
-Paragraph 21
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Fair Value (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value [Abstract]

Recurring Fair Value Measures [Table Text Block]



	Fair Value as of December 31, 2012
Recurring Fair Value Measures	Level 1		Level 2		Level 3	Total
Millions
Assets:
Investments
Available-for-sale Securities – Equity Securities		$18.0	—		—		$18.0
Available-for-sale Securities – Corporate Debt Securities	—			$8.8	—	8.8
Cash Equivalents	20.7		—		—	20.7
Total Fair Value of Assets		$38.7		$8.8	—		$47.5

Liabilities:
Deferred Compensation	—			$14.0	—		$14.0
Derivatives – Interest Rate Swap	—		0.7		—	0.7
Total Fair Value of Liabilities	—			$14.7	—		$14.7
Total Net Fair Value of Assets (Liabilities)		$38.7	$(5.9)		—		$32.8



	Fair Value as of December 31, 2011
Recurring Fair Value Measures	Level 1		Level 2		Level 3	Total
Millions
Assets:
Investments
Available-for-sale Securities – Equity Securities		$17.6	—		—		$17.6
Available-for-sale Securities – Corporate Debt Securities	—			$8.2	—	8.2
Cash Equivalents	11.4		—		—	11.4
Total Fair Value of Assets		$29.0		$8.2	—		$37.2

Liabilities:
Deferred Compensation	—			$12.8	—		$12.8
Derivatives – Interest Rate Swap	—			$0.4	—		$0.4
Total Fair Value of Liabilities	—			$13.2	—		$13.2
Total Net Fair Value of Assets (Liabilities)		$29.0	$(5.0)		—		$24.0

Recurring Fair Value Measures - Activity in Level 3 [Table Text Block]



Recurring Fair Value Measures Activity in Level 3	Debt Securities Issued by States of the United States (ARS)
Millions
Balance as of December 31, 2010		$6.7
Redeemed During the Period (a)	(6.7		)
Balance as of December 31, 2011		$—


(a)	The ARS were redeemed at carrying value on January 5, 2011.

Financial Instruments [Table Text Block]



Financial Instruments	Carrying Amount		Fair Value
Millions
Long-Term Debt, Including Current Portion
December 31, 2012		$1,018.1		$1,143.7
December 31, 2011		$863.3		$966.4

- Definition

Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.

+ References + Details

- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13476-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13467-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6447952&loc=d3e13220-108610

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 19
-Subparagraph a, b, c(1), d(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 14
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15
-Subparagraph b-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 18
-Subparagraph c(2), d, e, f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph a, c(1), c(2), c(3), d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Short-Term and Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2012

Short-Term and Long-Term Debt [Abstract]

Long-term Debt [Table Text Block]



Long-Term Debt
As of December 31	2012		2011
Millions
First Mortgage Bonds
4.86% Series Due 2013		$60.0		$60.0
6.94% Series Due 2014	18.0		18.0
7.70% Series Due 2016	20.0		20.0
8.17% Series Due 2019	42.0		42.0
5.28% Series Due 2020	35.0		35.0
4.85% Series Due 2021	15.0		15.0
4.95% Pollution Control Series F Due 2022	111.0		111.0
6.02% Series Due 2023	75.0		75.0
4.90% Series Due 2025	30.0		30.0
5.10% Series Due 2025	30.0		30.0
3.20% Series Due 2026	75.0		—
5.99% Series Due 2027	60.0		60.0
5.69% Series Due 2036	50.0		50.0
6.00% Series Due 2040	35.0		35.0
5.82% Series Due 2040	45.0		45.0
4.08% Series Due 2042	85.0		—
SWL&P First Mortgage Bonds 7.25% Series Due 2013	10.0		10.0
Senior Unsecured Notes 5.99% Due 2017	50.0		50.0
Variable Demand Revenue Refunding Bonds Series 1997 A, B, and C Due 2013 – 2020	27.5		28.2
Industrial Development Revenue Bonds 6.5% Due 2025	—		6.0
Industrial Development Variable Rate Demand Refunding Revenue Bonds Series 2006 Due 2025	27.8		27.8
Unsecured Term Loan Variable Rate Due 2014	75.0		75.0
Other Long-Term Debt, 1.0% – 8.0% Due 2013 – 2037	41.8		40.3
Total Long-Term Debt	1,018.1		863.3
Less: Due Within One Year	84.5		5.4
Net Long-Term Debt		$933.6		$857.9

On July 2, 2012, we issued $160.0 million of the Company’s First Mortgage Bonds (Bonds) in the private placement market in two series as follows:



Issue Date	Maturity Date	Principal Amount	Interest Rate
July 2, 2012	July 15, 2026	$75 Million	3.20%
July 2, 2012	July 15, 2042	$85 Million	4.08%

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

+ Details

Common Stock and Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2012

Common Stock and Earnings Per Share [Abstract]

Summary of Common Stock [Table Text Block]



Summary of Common Stock	Shares	Equity
	Thousands	Millions
Balance as of December 31, 2009	35,221		$613.4
Employee Stock Purchase Program	19	0.6
Invest Direct	346	11.7
Options and Stock Awards	51	4.4
Equity Issuance Program	180	6.0
Balance as of December 31, 2010	35,817		$636.1
Employee Stock Purchase Program	20	0.8
Invest Direct	437	17.2
Options and Stock Awards	109	6.7
Equity Issuance Program	400	16.0
Purchase of Non-Controlling Interest	222	8.8
Contributions to Pension	508	20.0
Balance as of December 31, 2011	37,513		$705.6
Employee Stock Purchase Program	20	0.8
Invest Direct	474	19.2
Options and Stock Awards	95	6.0
Equity Issuance Program	1,275	53.1
Balance as of December 31, 2012	39,377		$784.7

Reconciliation of Basic and Diluted Earnings Per Share [Table Text Block]



Reconciliation of Basic and Diluted
Earnings Per Share			Dilutive
Year Ended December 31	Basic		Securities	Diluted
Millions Except Per Share Amounts
2012
Net Income Attributable to ALLETE		$97.1			$97.1
Average Common Shares	37.6		—	37.6
Earnings Per Share		$2.59			$2.58
2011
Net Income Attributable to ALLETE		$93.8			$93.8
Average Common Shares	35.3		0.1	35.4
Earnings Per Share		$2.66			$2.65
2010
Net Income Attributable to ALLETE		$75.3			$75.3
Average Common Shares	34.2		0.1	34.3
Earnings Per Share		$2.20			$2.19

Other Income (Expense) (Tables)

12 Months Ended

Dec. 31, 2012

Other Income (Expense) [Abstract]

Other Income (Expense) [Table Text Block]



Year Ended December 31	2012		2011		2010
Millions
AFUDC – Equity		$5.1		$2.5		$4.2
Investment and Other Income	0.9		1.9		0.4
Total Other Income		$6.0		$4.4		$4.6

Income Tax Expense (Tables)

12 Months Ended

Dec. 31, 2012

Income Tax Expense [Abstract]

Income Tax Expense [Table Text Block]



Income Tax Expense
Year Ended December 31	2012			2011			2010
Millions
Current Tax Expense (Benefit)
Federal (a)	—			$1.4			$(23.0)
State (a)	$0.5			(1.6		)	1.3
Total Current Tax Expense (Benefit)	0.5			(0.2		)	(21.7		)
Deferred Tax Expense
Federal (b)	38.1			27.3			61.4
State (b)	(1.7		)	9.5			5.3
Change in Valuation Allowance (c)	2.0			(0.1		)	0.2
Investment Tax Credit Amortization	(0.9		)	(0.9		)	(0.9		)
Total Deferred Tax Expense	37.5			35.8			66.0
Total Income Tax Expense		$38.0			$35.6			$44.3

(a)

(b)


(c)	For the year ending December 31, 2012, the change in the valuation allowance is due to state renewable tax credits earned in 2012 which are not expected to be utilized within their allowable tax carryforward period.

Reconciliation of Taxes from Federal Statutory Rate to Total Income Tax Expense [Table Text Block]



Reconciliation of Taxes from Federal Statutory
Rate to Total Income Tax Expense
Year Ended December 31	2012			2011			2010
Millions
Income Before Non-Controlling Interest and Income Taxes		$135.1			$129.2			$119.1
Statutory Federal Income Tax Rate	35		%	35		%	35		%
Income Taxes Computed at 35 percent Statutory Federal Rate		$47.3			$45.2			$41.7
Increase (Decrease) in Tax Due to:
State Income Taxes – Net of Federal Income Tax Benefit	1.2			6.0			4.5
Impact of the PPACA	—			—			4.0
Deferred Accounting for Retail Portion of the PPACA	—			(2.9		)	—
2010 Rate Case Stipulation Agreement - Deferred Tax Reversal	—			(6.2		)	—
Regulatory Differences for Utility Plant	(2.2		)	(1.2		)	(2.0		)
Production Tax Credits	(7.6		)	(4.3		)	(1.6		)
Other	(0.7		)	(1.0		)	(2.3		)
Total Income Tax Expense		$38.0			$35.6			$44.3

Deferred Tax Assets and Liabilities [Table Text Block]



Deferred Tax Assets and Liabilities
As of December 31	2012			2011
Millions
Deferred Tax Assets
Employee Benefits and Compensation		$120.2			$132.7
Property Related	59.8			56.4
NOL Carryforwards	90.8			61.7
Tax Credit Carryforwards	28.3			12.2
Other	24.6			20.4
Gross Deferred Tax Assets	323.7			283.4
Deferred Tax Asset Valuation Allowance	(2.4		)	(0.4		)
Total Deferred Tax Assets		$321.3			$283.0
Deferred Tax Liabilities
Property Related		$577.1			$482.7
Regulatory Asset for Benefit Obligations	104.3			117.9
Unamortized Investment Tax Credits	11.9			12.8
Partnership Basis Differences	28.6			24.4
Other	30.1			24.0
Total Deferred Tax Liabilities		$752.0			$661.8
Net Deferred Income Taxes		$430.7			$378.8
Recorded as:
Net Current Deferred Tax Liabilities (a)		$6.9			$5.2
Net Long-Term Deferred Tax Liabilities	423.8			373.6
Net Deferred Income Taxes		$430.7			$378.8


(a)	Included in Other Current Liabilities.

NOL and Tax Credit Carryforwards [Table Text Block]



NOL and Tax Credit Carryforwards
Year Ended December 31	2012		2011
Millions
Federal NOL carryforwards (a)		$244.1		$162.0
Federal tax credit carryforwards	$16.0		$8.4
State NOL carryforwards (a) (b)	$90.6		$73.1
State tax credit carryforwards (c)	$10.3		$3.8


(a)	Pretax amounts


(b)	Net of $0.4 million valuation allowance.


(c)	Net of $2.0 million valuation allowance.

Gross Unrecognized Income Tax Benefits [Table Text Block]



Gross Unrecognized Income Tax Benefits	2012			2011			2010
Millions
Balance at January 1		$11.4			$12.3			$9.5
Reductions for Tax Positions Related to the Current Year	—			—			(0.2		)
Additions for Tax Positions Related to Prior Years	—			—			4.4
Reductions for Tax Positions Related to Prior Years	(8.7		)	(0.9		)	—
Reductions for Settlements	—			—			(0.3		)
Reductions for Expired Statute of Limitations	—			—			(1.1		)
Balance as of December 31		$2.7			$11.4			$12.3

- Definition

Tabular disclosure of tax positions taken in the tax returns filed or to be filed for which it is more likely than not that the tax position will not be sustained upon examination by taxing authorities (i.e., uncertain tax positions) and other types of income tax contingencies, including: (1) the policy on classification of interest and penalties; (2) a tabular reconciliation of the total amounts of unrecognized tax benefits at the beginning and end of the period; the total amount(s) of: (3) unrecognized tax benefits that, if recognized, would affect the effective tax rate, and (4) interest and penalties recognized in each of the income statement and balance sheet; (5) for positions for which it is reasonably possible that the total amounts unrecognized will significantly change within 12 months of the reporting date the: (i) nature of the uncertainty, (ii) nature of the event that could occur that would cause the change, and (iii) an estimate of the range of the reasonably possible change or a statement that an estimate of the range cannot be made; and (6) a description of tax years that remain subject to examination by major tax jurisdictions.

+ References + Details

Pension and Other Postretirement Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2012

Defined Benefit Plan Disclosure [Line Items]

Estimated Future Benefit Payments [Table Text Block]



Estimated Future Benefit Payments
			Postretirement
	Pension		Health and Life
Millions
2013		$31.2		$7.6
2014		$32.1		$8.2
2015		$33.2		$8.9
2016		$34.4		$9.4
2017		$35.5		$9.7
Years 2018 – 2022		$189.4		$52.0

Defined Benefit Costs Recorded in Regulatory Long-Term Assets and Accumulated Other Comprehensive Income Expected to be Recognized over Next Fiscal Year [Table Text Block]



	Pension		Postretirement Health and Life
Millions
Net Loss		$21.4		$1.6
Prior Service Cost (Credit)	0.3		(2.5		)
Total Pension and Postretirement Health and Life Cost (Credit)		$21.7	$(0.9)

Weighted-Average Assumptions Used to Determine Benefit Obligation and Net Periodic Benefit Costs [Table Text Block]



Weighted-Average Assumptions Used to Determine Benefit Obligation
As of December 31	2012	2011
Discount Rate
Pension	4.10%	4.54%
Postretirement Health and Life	4.13%	4.56%
Rate of Compensation Increase	4.3 - 4.6%	4.3 - 4.6%
Health Care Trend Rates
Trend Rate	9.25%	10%
Ultimate Trend Rate	5%	5%
Year Ultimate Trend Rate Effective	2019	2018



Weighted-Average Assumptions Used to Determine Net Periodic Benefit Costs
Year Ended December 31	2012	2011	2010
Discount Rate	4.54 - 4.56%	5.36 - 5.40%	5.81%
Expected Long-Term Return on Plan Assets
Pension	8.25%	8.5%	8.5%
Postretirement Health and Life	6.6 - 8.25%	6.8 - 8.5%	6.8 - 8.5%
Rate of Compensation Increase	4.3 - 4.6%	4.3 - 4.6%	4.3 - 4.6%

Plan Asset Allocations, Actual and Target [Table Text Block]



Actual Plan Asset Allocations
	Pension				Postretirement Health and Life (a)
	2012		2011		2012		2011
Equity Securities	54	%	52	%	56	%	51	%
Debt Securities	28	%	27	%	35	%	39	%
Private Equity	13	%	16	%	9	%	10	%
Real Estate	5	%	5	%	—		—
	100	%	100	%	100	%	100	%


(a)	Includes VEBAs and irrevocable grantor trusts.



Plan Asset Target Allocations
			Postretirement
	Pension		Health and Life (a)
Equity Securities	52	%	48	%
Debt Securities	30	%	34	%
Real Estate	9	%	9	%
Private Equity	9	%	9	%
	100	%	100	%


(a)	Includes VEBAs and irrevocable grantor trusts.

Recurring Fair Value Measures [Table Text Block]



	Fair Value as of December 31, 2012
Recurring Fair Value Measures	Level 1		Level 2		Level 3	Total
Millions
Assets:
Investments
Available-for-sale Securities – Equity Securities		$18.0	—		—		$18.0
Available-for-sale Securities – Corporate Debt Securities	—			$8.8	—	8.8
Cash Equivalents	20.7		—		—	20.7
Total Fair Value of Assets		$38.7		$8.8	—		$47.5

Liabilities:
Deferred Compensation	—			$14.0	—		$14.0
Derivatives – Interest Rate Swap	—		0.7		—	0.7
Total Fair Value of Liabilities	—			$14.7	—		$14.7
Total Net Fair Value of Assets (Liabilities)		$38.7	$(5.9)		—		$32.8



	Fair Value as of December 31, 2011
Recurring Fair Value Measures	Level 1		Level 2		Level 3	Total
Millions
Assets:
Investments
Available-for-sale Securities – Equity Securities		$17.6	—		—		$17.6
Available-for-sale Securities – Corporate Debt Securities	—			$8.2	—	8.2
Cash Equivalents	11.4		—		—	11.4
Total Fair Value of Assets		$29.0		$8.2	—		$37.2

Liabilities:
Deferred Compensation	—			$12.8	—		$12.8
Derivatives – Interest Rate Swap	—			$0.4	—		$0.4
Total Fair Value of Liabilities	—			$13.2	—		$13.2
Total Net Fair Value of Assets (Liabilities)		$29.0	$(5.0)		—		$24.0

Recurring Fair Value Measures - Activity in Level 3 [Table Text Block]



Recurring Fair Value Measures Activity in Level 3	Debt Securities Issued by States of the United States (ARS)
Millions
Balance as of December 31, 2010		$6.7
Redeemed During the Period (a)	(6.7		)
Balance as of December 31, 2011		$—


(a)	The ARS were redeemed at carrying value on January 5, 2011.

Pension [Member]

Defined Benefit Plan Disclosure [Line Items]

Obligation and Funded Status [Table Text Block]



Pension Obligation and Funded Status
Year Ended December 31	2012			2011
Millions
Accumulated Benefit Obligation		$598.7			$550.6
Change in Benefit Obligation
Obligation, Beginning of Year		$597.5			$525.6
Service Cost	9.1			7.6
Interest Cost	26.4			27.4
Actuarial Loss	38.5			54.6
Benefits Paid	(30.9		)	(28.6		)
Participant Contributions	11.5			10.9
Obligation, End of Year		$652.1			$597.5
Change in Plan Assets
Fair Value, Beginning of Year		$432.4			$382.0
Actual Return on Plan Assets	38.7			33.2
Employer Contribution	19.9			45.8
Benefits Paid	(30.9		)	(28.6		)
Fair Value, End of Year		$460.1			$432.4
Funded Status, End of Year	$(192.0)			$(165.1)

Net Pension Amounts Recognized in Consolidated Balance Sheet Consist of:
Current Liabilities	$(1.1)			$(1.1)
Non-Current Liabilities	$(190.9)			$(164.0)

Unrecognized Benefit Costs [Table Text Block]



Unrecognized Pension Costs
Year Ended December 31	2012		2011
Millions
Net Loss		$286.8		$269.0
Prior Service Cost	0.7		1.1
Total Unrecognized Pension Costs		$287.5		$270.1

Components of Net Periodic Expense [Table Text Block]



Components of Net Periodic Pension Expense
Year Ended December 31	2012			2011			2010
Millions
Service Cost		$9.1			$7.6			$6.2
Interest Cost	26.4			27.4			26.2
Expected Return on Plan Assets	(35.4		)	(34.6		)	(33.7		)
Amortization of Loss	17.5			12.1			6.6
Amortization of Prior Service Cost	0.3			0.3			0.5
Net Pension Expense		$17.9			$12.8			$5.8

Other Changes in Defined Benefit Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income and Regulatory Assets [Table Text Block]



Other Changes in Pension Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income and Regulatory Assets
Year Ended December 31	2012			2011
Millions
Net Loss		$35.2			$56.1
Amortization of Prior Service Cost	(0.3		)	(0.3		)
Amortization of Loss	(17.5		)	(12.2		)
Total Recognized in Other Comprehensive Income and Regulatory Assets		$17.4			$43.6

Information for Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets [Table Text Block]



Information for Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets
Year Ended December 31	2012		2011
Millions
Projected Benefit Obligation		$652.1		$597.5
Accumulated Benefit Obligation		$598.7		$550.6
Fair Value of Plan Assets		$460.1		$432.4

Recurring Fair Value Measures [Table Text Block]



	Fair Value as of December 31, 2012
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Equity Securities:
U.S. Large-cap (a)		$43.0		$36.0	—			$79.0
U.S. Mid-cap Growth (a)	18.3		15.3		—		33.6
U.S. Small-cap (a)	18.3		15.3		—		33.6
International	50.5		45.9		—		96.4
Debt Securities:
Mutual Funds	72.5		—		—		72.5
Fixed Income	10.4		50.8		—		61.2
Other Types of Investments:
Private Equity Funds	—		—			$58.9	58.9
Real Estate	—		—		24.9		24.9
Total Fair Value of Assets		$213.0		$163.3		$83.8		$460.1

(a)



	Fair Value as of December 31, 2011
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Equity Securities:
U.S. Large-cap (a)		$32.1		$37.3	—			$69.4
U.S. Mid-cap Growth (a)	13.5		15.8		—		29.3
U.S. Small-cap (a)	13.1		15.2		—		28.3
International	—		75.1		—		75.1
ALLETE	21.3		—		—		21.3
Debt Securities:
Mutual Funds	72.8		—		—		72.8
Fixed Income	—		45.5		—		45.5
Other Types of Investments:
Private Equity Funds	—		—			$69.0	69.0
Real Estate	—		—		21.7		21.7
Total Fair Value of Assets		$152.8		$188.9		$90.7		$432.4

(a)

Recurring Fair Value Measures - Activity in Level 3 [Table Text Block]



Recurring Fair Value Measures
Activity in Level 3	Private Equity Funds			Real Estate
Millions
Balance as of December 31, 2011		$69.0			$21.7
Actual Return on Plan Assets	(9.7		)	3.4
Purchases, sales, and settlements, net	(0.4		)	(0.2		)
Balance as of December 31, 2012		$58.9			$24.9



Recurring Fair Value Measures
Activity in Level 3	Equity Securities (ARS)			Private Equity Funds			Real Estate
Millions
Balance as of December 31, 2010		$6.7			$50.7			$20.1
Actual Return on Plan Assets	—			30.9			3.5
Purchases, sales, and settlements, net	(6.7		)	(12.6		)	(1.9		)
Balance as of December 31, 2011	—				$69.0			$21.7

Postretirement Health and Life [Member]

Defined Benefit Plan Disclosure [Line Items]

Obligation and Funded Status [Table Text Block]



Postretirement Health and Life Obligation and Funded Status
Year Ended December 31	2012			2011
Millions
Change in Benefit Obligation
Obligation, Beginning of Year		$210.6			$204.1
Service Cost	4.2			3.8
Interest Cost	9.4			10.8
Actuarial Gain	(43.2		)	(2.9		)
Participant Contributions	2.6			2.5
Plan Amendments	(5.3		)	—
Benefits Paid	(9.5		)	(7.7		)
Obligation, End of Year		$168.8			$210.6
Change in Plan Assets
Fair Value, Beginning of Year		$121.0			$114.7
Actual Return on Plan Assets	14.3			—
Employer Contribution	2.3			11.4
Participant Contributions	2.5			2.5
Benefits Paid	(9.1		)	(7.6		)
Fair Value, End of Year		$131.0			$121.0
Funded Status, End of Year	$(37.8)			$(89.6)

Net Postretirement Health and Life Amounts Recognized in Consolidated Balance Sheet Consist of:
Current Liabilities	$(0.8)			$(0.9)
Non-Current Liabilities	$(37.0)			$(88.7)

Unrecognized Benefit Costs [Table Text Block]



Unrecognized Postretirement Health and Life Costs
Year Ended December 31	2012			2011
Millions
Net Loss		$23.5			$78.5
Prior Service Credit	(13.1		)	(9.5		)
Transition Obligation	—			0.1
Total Unrecognized Postretirement Health and Life Costs		$10.4			$69.1

Components of Net Periodic Expense [Table Text Block]



Components of Net Periodic Postretirement Health and Life Expense
Year Ended December 31	2012			2011			2010
Millions
Service Cost		$4.2			$3.8			$4.8
Interest Cost	9.4			10.8			10.9
Expected Return on Plan Assets	(9.9		)	(9.7		)	(9.5		)
Amortization of Prior Service Credit	(1.7		)	(1.7		)	(0.1		)
Amortization of Loss	7.5			8.5			4.8
Amortization of Transition Obligation	0.1			0.1			2.5
Net Postretirement Health and Life Expense		$9.6			$11.8			$13.4

Other Changes in Defined Benefit Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income and Regulatory Assets [Table Text Block]



Other Changes in Postretirement Benefit Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income and Regulatory Assets
Year Ended December 31	2012		2011
Millions
Net (Gain) Loss	$(47.5)			$6.9
Prior Service Credit Arising During the Period	(5.3	)	—
Amortization of Prior Service Credit	1.7		1.7
Amortization of Transition Obligation	(0.1	)	(0.1		)
Amortization of Loss	(7.5	)	(8.5		)
Total Recognized in Other Comprehensive Income and Regulatory Assets	$(58.7)		—

Sensitivity of a One-Percentage-Point Change in Health Care Trend Rates [Table Text Block]



Sensitivity of a One-Percentage-Point Change in Health Care Trend Rates
	One Percent		One Percent
	Increase		Decrease
Millions
Effect on Total of Postretirement Health and Life Service and Interest Cost		$2.0	$(1.6)
Effect on Postretirement Health and Life Obligation		$18.2	$(15.1)

Recurring Fair Value Measures [Table Text Block]



	Fair Value as of December 31, 2012
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Equity Securities:
U.S. Large-cap (a)		$16.7	—		—			$16.7
U.S. Mid-cap Growth (a)	13.2		—		—		13.2
U.S. Small-cap (a)	13.3		—		—		13.3
International	30.3		—		—		30.3
Debt Securities:
Mutual Funds	25.5		—		—		25.5
Fixed Income	0.2			$18.3	—		18.5
Other Types of Investments:
Private Equity Funds	—		—			$13.5	13.5
Total Fair Value of Assets		$99.2		$18.3		$13.5		$131.0


(a)	The underlying investments classified under U.S. Equity Securities consist of mutual funds (Level 1).



	Fair Value as of December 31, 2011
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Equity Securities:
U.S. Large-cap (a)		$15.9	—		—			$15.9
U.S. Mid-cap Growth (a)	11.5		—		—		11.5
U.S. Small-cap (a)	11.2		—		—		11.2
International	25.1		—		—		25.1
Debt Securities:
Mutual Funds	24.1		—		—		24.1
Fixed Income	0.3			$18.9	—		19.2
Other Types of Investments:
Private Equity Funds	—		—			$14.0	14.0
Total Fair Value of Assets		$88.1		$18.9		$14.0		$121.0


(a)	The underlying investments classified under U.S. Equity Securities consist of mutual funds (Level 1).

Recurring Fair Value Measures - Activity in Level 3 [Table Text Block]



Recurring Fair Value Measures
Activity in Level 3	Private Equity Funds
Millions
Balance as of December 31, 2011		$14.0
Actual Return on Plan Assets	0.2
Purchases, sales, and settlements, net	(0.7		)
Balance as of December 31, 2012		$13.5



Recurring Fair Value Measures
Activity in Level 3	Private Equity Funds
Millions
Balance as of December 31, 2010		$12.4
Actual Return on Plan Assets	1.1
Purchases, sales, and settlements, net	0.5
Balance as of December 31, 2011		$14.0

Employee Stock and Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2012

Employee Stock and Incentive Plans [Abstract]

Employee Stock Ownership Plan [Table Text Block]



Year Ended December 31	2012		2011		2010
Millions
ESOP Shares
Allocated	2.2		2.2		2.2
Unallocated	0.7		1.0		1.3
Total	2.9		3.2		3.5
Fair Value of Unallocated Shares		$28.7		$42.0		$48.4

Share-Based Compensation Expense [Table Text Block]

The following share-based compensation expense amounts were recognized in our Consolidated Statement of Income for the periods presented.



Share-Based Compensation Expense
Year Ended December 31	2012		2011		2010
Millions
Stock Options	—		—			$0.1
Performance Shares		$1.4		$1.1	1.5
Restricted Stock Units	0.7		0.5		0.6
Total Share-Based Compensation Expense		$2.1		$1.6		$2.2
Income Tax Benefit		$0.9		$0.7		$0.9

Non-Qualified Stock Options [Table Text Block]

Non-Qualified Stock Options. The following table presents information regarding our outstanding stock options as of December 31, 2012.



	2012			2011			2010
	Number of Options	Weighted-Average Exercise Price		Number of Options	Weighted-Average Exercise Price		Number of Options	Weighted-Average Exercise Price
Outstanding as of January 1,	460,234		$41.68	560,887		$40.69	646,235		$40.05
Granted (a)	—	—		—	—		—	—
Exercised	49,075		$35.84	80,798		$34.25	40,769		$27.76
Forfeited	15,481		$44.86	19,855		$43.96	44,579		$43.16
Outstanding as of December 31,	395,678		$42.28	460,234		$41.68	560,887		$40.69
Exercisable as of December 31,	395,678		$41.71	460,234		$41.59	523,491		$39.76


(a)	Stock options have not been granted since 2008. The weighted-average grant-date intrinsic value of options granted in 2008 was $6.18.

Stock Options, by Exercise Price Range [Table Text Block]



	Range of Exercise Price
As of December 31, 2012	$23.79 to $26.91		$37.76 to $41.35		$44.15 to $48.65
Options Outstanding and Exercisable:
Number Outstanding and Exercisable	1,340		236,052		158,286
Weighted Average Remaining Contractual Life (Years)	0.1		3.5		3.6
Weighted Average Exercise Price		$23.79		$39.64		$46.38

Performance Shares [Table Text Block]

Performance Shares. The following table presents information regarding our non-vested performance shares as of December 31, 2012.



	2012				2011				2010
	Number of Shares		Weighted- Average Grant Date Fair Value		Number of Shares		Weighted- Average Grant Date Fair Value		Number of Shares		Weighted- Average Grant Date Fair Value
Non-vested as of January 1,	128,333			$36.54	122,489			$38.15	121,825			$41.96
Granted (a)	38,764			$44.70	39,312			$41.00	49,302			$35.44
Awarded	(41,009	)		$34.25	(32,368	)		$48.10	—		—
Unearned Grant Award	(17,575	)		$34.25	—		—		(22,909	)		$54.50
Forfeited	(614	)		$34.49	(1,100	)		$34.35	(25,729	)		$36.45
Non-vested as of December 31,	107,899			$40.73	128,333			$36.54	122,489			$38.15

(a) Shares granted includes accrued dividends.

Restricted Stock Units [Table Text Block]

Restricted Stock Units. The following table presents information regarding our available restricted stock units as of December 31, 2012.



	2012				2011				2010
	Number of Shares		Weighted- Average Grant Date Fair Value		Number of Shares		Weighted- Average Grant Date Fair Value		Number of Shares		Weighted- Average Grant Date Fair Value
Available as of January 1,	63,464			$32.57	43,803			$30.61	28,983			$29.41
Granted (a)	18,162			$40.83	20,136			$36.74	26,589			$31.83
Awarded	(24,707	)		$29.43	(215	)		$30.30	(3,091	)		$29.75
Forfeited	(504	)		$31.80	(260	)		$29.41	(8,678	)		$30.62
Available as of December 31,	56,415			$36.61	63,464			$32.57	43,803			$30.61

(a) Shares granted includes accrued dividends.

- Definition

Tabular disclosure of the description of the plan, the basis for determining contributions, including the employee groups covered, and the nature and effect of significant matters affecting comparability of information for all periods presented. For leveraged ESOPs and pension reversion ESOPs, the disclosure may include the basis for releasing shares and how dividends on allocated and unallocated shares are used. Disclosure may also include a description of the accounting policies followed for ESOP transactions, including the method of measuring compensation, the classification of dividends on ESOP shares, and the treatment of ESOP shares for EPS computations. If the employer has both old ESOP shares for which it does not adopt the latest guidance and new ESOP shares for which the new guidance is required, the accounting policies for both blocks of shares may be described. Disclosure may also include he amount of compensation cost recognized during the period, the number of allocated shares, committed-to-be-released shares, and suspense shares held by the ESOP at the balance-sheet date, the fair value of unearned ESOP shares at the balance-sheet date for shares accounted for under the latest guidance, the existence and nature of any repurchase obligation, including disclosure of the fair value of the shares allocated as of the balance sheet date, which are subject to a repurchase obligation.

+ References + Details

Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2012

Quarterly Financial Data (Unaudited) [Abstract]

Quarterly Financial Data (Unaudited) [Table Text Block]



Quarter Ended	Mar. 31		Jun. 30		Sept. 30		Dec. 31
Millions Except Earnings Per Share
2012
Operating Revenue		$240.0		$216.4		$248.8		$256.0
Operating Income		$38.4		$23.3		$45.6		$47.9
Net Income Attributable to ALLETE		$24.4		$14.4		$29.4		$28.9
Earnings Per Share of Common Stock
Basic		$0.66		$0.39		$0.78		$0.76
Diluted		$0.66		$0.39		$0.78		$0.75
2011
Operating Revenue		$242.2		$219.9		$226.9		$239.2
Operating Income		$50.8		$26.1		$38.9		$34.2
Net Income Attributable to ALLETE		$37.2		$17.0		$20.5		$19.1
Earnings Per Share of Common Stock
Basic		$1.07		$0.49		$0.57		$0.53
Diluted		$1.07		$0.48		$0.57		$0.53

Operations and Significant Accounting Policies (Details)
shares in Millions, $ in Millions

3 Months Ended

12 Months Ended

Sep. 30, 2011

USD ($)

Dec. 31, 2012

USD ($)

Customers

Dec. 31, 2011

USD ($)

Dec. 31, 2010

USD ($)

Non-Controlling Interest in Subsidiaries [Abstract]

Purchase of Non-Controlling Interest at Book Value

$ 8.8

Purchase of Non-Controlling Interest, Shares Issued | shares

0.2

Trade Accounts Receivable [Abstract]

Billed

$ 70.4

$ 63.7

Unbilled

17.4

15.6

Less: Allowance for Doubtful Accounts

1.0

0.9

Total Trade Accounts Receivable

86.8

78.4

Income Taxes Receivable

2.2

1.3

Total Accounts Receivable - Net

89.0

79.7

Inventories [Abstract]

Fuel

28.0

28.6

Materials and Supplies

41.8

40.5

Total Inventories

69.8

69.1

Impairement of Long-Lived Assets [Abstract]

Land Impairment

0.0

1.7

Prepayments and Other Current Assets [Abstract]

Deferred Fuel Adjustment Clause

22.5

17.5

Other

11.1

9.6

Total Prepayments and Other Current Assets

33.6

27.1

Other Current Liabilities [Abstract]

Customer Deposits

^[1]

28.8

16.3

Other

33.8

29.3

Total Other Current Liabilities

62.6

45.6

Other Non-Current Liabilities [Abstract]

Asset Retirement Obligation

77.9

57.0

$ 50.3

Other

45.4

48.1

Total Other Non-Current Liabilities

$ 123.3

$ 105.1

Income Tax Disclosure [Abstract]

More Likely Than Not Definition

50.00%

Municipal Customers [Member]

Customer Information [Line Items]

Number of Customers | Customers

Non-Affiliated Private Utility [Member]

Customer Information [Line Items]

Number of Customers | Customers

Retail Customers [Member]

Customer Information [Line Items]

Number of Customers | Customers

143,000

Electric [Member]

Customer Information [Line Items]

Number of Customers | Customers

15,000

Natural Gas [Member]

Customer Information [Line Items]

Number of Customers | Customers

12,000

Water [Member]

Customer Information [Line Items]

Number of Customers | Customers

10,000

[1]	2012 primarily due to customer security deposits for capital expenditures relating to a transmission project.

Operations and Significant Accounting Policies - Minnesota Land Acres (Details)	Dec. 31, 2012
Investments and Other [Member]
Business Segments [Line Items]
Number of acres of land in Minnesota (in acres)	6,100

Operations and Significant Accounting Policies - Supplemental Statement of Cash Flow Information (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Supplemental Cash Flow Information [Abstract]

Cash Paid During the Period for Interest - Net of Amounts Capitalized

$ 42.7

$ 43.2

$ 35.7

Cash Received During the Period for Income Taxes

^[1]

0.0

(11.4)

(54.2)

Noncash Investing and Financing Activities [Abstract]

Increase in Accounts Payable for Capital Additions to Property, Plant and Equipment

20.2

5.9

7.5

Capitalized Asset Retirement Costs

17.1

0.3

2.8

AFUDC - Equity

5.1

2.5

4.2

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

ALLETE Common Stock Contributed to Pension Plan

$ 0.0

(20.0)

$ 0.0

Pension [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

ALLETE Common Stock Contributed to Pension Plan

$ 20.0

[1]	Due to bonus depreciation provisions in 2009 and 2010 federal legislation, NOLs were generated which resulted in little or no estimated tax payments, and refunds were received from NOL carrybacks against prior years’ taxable income.

Operations and Significant Accounting Policies - Investments and Other (Details)	12 Months Ended
	Dec. 31, 2012 MW
Long-term Contract for Purchase of Electric Power [Line Items]
Real Estate Sales Revenue Recognition, Minimum Contract Price Cash Collections Requirement	20.00%
Square Butte PPA [Member]
Long-term Contract for Purchase of Electric Power [Line Items]
Output Purchased (Percent)	50.00%
Output Purchased (MW)	227.5

Operations and Significant Accounting Policies - Concentraion of Credit Risk (Details) $ in Millions	12 Months Ended
	Dec. 31, 2012 USD ($) Customers	Dec. 31, 2011 USD ($)	Dec. 31, 2010
Customer Information [Line Items]
Major Customer, Percent of Total Revenue	12.30%	12.80%	12.50%
NewPage Bankruptcy Pre-Petition Receivable	$ 3.2
Large Power Customer [Member]
Customer Information [Line Items]
Number of Customers \| Customers	9
Large Power Customers, Accounts Receivable	$ 11.6	$ 9.3

Business Segments (Details) $ in Millions	3 Months Ended								12 Months Ended
Business Segments (Details) $ in Millions	Dec. 31, 2012 USD ($)	Sep. 30, 2012 USD ($)	Jun. 30, 2012 USD ($)	Mar. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Sep. 30, 2011 USD ($)	Jun. 30, 2011 USD ($)	Mar. 31, 2011 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)
Business Segments [Line Items]
Operating Revenue	$ 256.0	$ 248.8	$ 216.4	$ 240.0	$ 239.2	$ 226.9	$ 219.9	$ 242.2	$ 961.2	$ 928.2	$ 907.0
Fuel and Purchased Power Expense									308.7	306.6	325.1
Operating and Maintenance Expense									397.1	381.2	365.6
Depreciation Expense									100.2	90.4	80.5
Operating Income (Loss)	47.9	45.6	23.3	38.4	34.2	38.9	26.1	50.8	155.2	150.0	135.8
Interest Expense									(45.5)	(43.6)	(39.2)
Equity Earnings in ATC									19.4	18.4	17.9
Other Income									6.0	4.4	4.6
Income (Loss) Before Non-Controlling Interest and Income Taxes									135.1	129.2	119.1
Income Tax Expense (Benefit)									38.0	35.6	44.3
Net Income (Loss)									97.1	93.6	74.8
Less: Non-Controlling Interest in Subsidiaries									0.0	(0.2)	(0.5)
Net Income (Loss) Attributable to ALLETE	28.9	$ 29.4	$ 14.4	$ 24.4	19.1	$ 20.5	$ 17.0	$ 37.2	97.1	93.8	75.3
Total Assets	3,253.4				2,876.0				3,253.4	2,876.0	2,609.1
Capital Additions									432.2	246.8	260.0
Regulated Operations [Member]
Business Segments [Line Items]
Operating Revenue									874.4	851.9	835.5
Fuel and Purchased Power Expense									308.7	306.6	325.1
Operating and Maintenance Expense									310.0	301.5	292.3
Depreciation Expense									93.9	85.4	76.1
Operating Income (Loss)									161.8	158.4	142.0
Interest Expense									(39.8)	(35.8)	(32.3)
Equity Earnings in ATC									19.4	18.4	17.9
Other Income									5.1	2.6	3.8
Income (Loss) Before Non-Controlling Interest and Income Taxes									146.5	143.6	131.4
Income Tax Expense (Benefit)									50.4	43.2	51.6
Net Income (Loss)									96.1	100.4	79.8
Less: Non-Controlling Interest in Subsidiaries									0.0	0.0	0.0
Net Income (Loss) Attributable to ALLETE									96.1	100.4	79.8
Total Assets	$ 2,962.4				2,579.8				2,962.4	2,579.8	2,375.4
Capital Additions									$ 418.2	228.0	256.4
Investments and Other [Member]
Business Segments [Line Items]
Number of acres of land in Minnesota (in acres)	6,100								6,100
Operating Revenue									$ 86.8	76.3	71.5
Fuel and Purchased Power Expense									0.0	0.0	0.0
Operating and Maintenance Expense									87.1	79.7	73.3
Depreciation Expense									6.3	5.0	4.4
Operating Income (Loss)									(6.6)	(8.4)	(6.2)
Interest Expense									(5.7)	(7.8)	(6.9)
Equity Earnings in ATC									0.0	0.0	0.0
Other Income									0.9	1.8	0.8
Income (Loss) Before Non-Controlling Interest and Income Taxes									(11.4)	(14.4)	(12.3)
Income Tax Expense (Benefit)									(12.4)	(7.6)	(7.3)
Net Income (Loss)									1.0	(6.8)	(5.0)
Less: Non-Controlling Interest in Subsidiaries									0.0	(0.2)	(0.5)
Net Income (Loss) Attributable to ALLETE									1.0	(6.6)	(4.5)
Total Assets	$ 291.0				$ 296.2				291.0	296.2	233.7
Capital Additions									$ 14.0	$ 18.8	$ 3.6

Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment - Net	$ 2,347.6	$ 1,982.7
Asset Retirement Obligation [Roll Forward]
Beginning Obligation	57.0	50.3
Accretion Expense	3.8	6.4
Additional Liabilities Incurred	17.1	0.3	$ 2.8
Ending Obligation	77.9	57.0	$ 50.3
Regulated Utiity [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	3,232.9	2,794.8
Construction Work in Progress	151.8	155.0
Accumulated Depreciation	(1,102.8)	(1,024.6)
Property, Plant and Equipment - Net	$ 2,281.9	1,925.2
Estimated Useful Life - Generation	3 to 35 years
Estimated Useful Life - Transmission	42 to 61 years
Estimated Useful Life - Distribution	14 to 65 years
Non-Rate Base Energy Operations and Other Plant [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	$ 118.0	106.4
Construction Work in Progress	4.2	2.3
Accumulated Depreciation	(56.7)	(51.4)
Property, Plant and Equipment - Net	65.5	57.3
Other Plant - Net	$ 0.2	$ 0.2
Estimated Useful Life - Non-Rate Base Operations	3 to 61 years
Estimated Useful Life - Other Plant	5 to 25 years

Jointly-Owned Facilities (Details) $ in Millions	Dec. 31, 2012 USD ($) MW
Jointly-Owned Facilities [Line Items]
Plant in Service	$ 435.9
Accumulated Depreciation	188.5
Construction Work in Progress	50.4
Boswell Unit 4 [Member]
Jointly-Owned Facilities [Line Items]
Plant in Service	413.1
Accumulated Depreciation	188.1
Construction Work in Progress	$ 25.0
% Ownership	80.00%
Generating Unit Capacity (MW) \| MW	585
% Not Owned	20.00%
CapX2020 [Member]
Jointly-Owned Facilities [Line Items]
Plant in Service	$ 22.8
Accumulated Depreciation	0.4
Construction Work in Progress	$ 25.4
Number of Projects	3
CapX2020 [Member] \| Minimum [Member]
Jointly-Owned Facilities [Line Items]
% Ownership	9.30%
CapX2020 [Member] \| Maximum [Member]
Jointly-Owned Facilities [Line Items]
% Ownership	14.70%

Regulatory Matters - Electric Rates (Details) $ in Millions	Dec. 31, 2012 USD ($) Customers Years MW	Jun. 01, 2011
Municipal Customers [Member]
Rate Regulation [Line Items]
Number of Customers	16
Non-Affiliated Private Utility [Member]
Rate Regulation [Line Items]
Number of Customers	1
MPUC 2010 MN Rate Case [Member] \| Electric Rates [Member] \| Retail Customers [Member]
Rate Regulation [Line Items]
Approved Rate of Return on Common Equity		10.38%
Approved Percentage of Capital Structure Related to Equity		54.29%
FERC-Approved Wholesale Rates [Member] \| Electric Rates [Member] \| Municipal Customers [Member]
Rate Regulation [Line Items]
Number of Customers	16
Length of Notice Required to Terminate (Years) \| Years	3
FERC-Approved Wholesale Rates [Member] \| Electric Rates [Member] \| Non-Affiliated Private Utility [Member]
Rate Regulation [Line Items]
Number of Customers	1
Length of Notice Required to Terminate (Years) \| Years	2
Average Monthly Demand (in MWs) \| MW	17
PSCW 2012 Wisconsin Rate Case [Member] \| Retail Customers [Member]
Rate Regulation [Line Items]
Approved Rate of Return on Common Equity	10.90%
Approved Rate Increase or Decrease	2.40%
Amount Of Estimated Additional Revenue \| $	$ 1.7
PSCW 2012 Wisconsin Rate Case [Member] \| Natural Gas Rates [Member] \| Retail Customers [Member]
Rate Regulation [Line Items]
Approved Rate Increase or Decrease	(2.00%)
PSCW 2012 Wisconsin Rate Case [Member] \| Electric Rates [Member] \| Retail Customers [Member]
Rate Regulation [Line Items]
Approved Rate Increase or Decrease	1.20%
PSCW 2012 Wisconsin Rate Case [Member] \| Water Rates [Member] \| Retail Customers [Member]
Rate Regulation [Line Items]
Approved Rate Increase or Decrease	13.80%

Regulatory Matters - Boswell Mercury Emission Reduction Plan (Details) - Boswell Unit 4 [Member] $ in Millions	Dec. 31, 2012 USD ($)
Schedule of Utility Generating Facilities [Line Items]
Estimated Environmental Compliance Costs - Minimum	$ 350
Estimated Environmental Compliance Costs - Maximum	$ 400

Regulatory Matters - The Patient Protection and Affordable Care Act of 2010 (PPACA) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Unusual or Infrequent Item [Line Items]
Deferred Income Tax Expense (Benefit)		$ 37.5	$ 35.8	$ 66.0
Non-Current Regulatory Asset		340.3	345.9
PPACA Elimination of Medicare Part D [Member]
Unusual or Infrequent Item [Line Items]
Reversal of Previously Recorded Tax Benefit		0.0	0.0	4.0
Deferred Income Tax Expense (Benefit)	$ 2.9	0.0	$ (2.9)	$ 0.0
Non-Current Regulatory Asset		$ 5.0

- Definition

The component of income tax expense for the period representing the increase (decrease) in the entity's deferred tax assets and liabilities pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Deferred Tax Expense (or Benefit)
-URI http://asc.fasb.org/extlink&oid=6510177

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.7)
-URI http://asc.fasb.org/extlink&oid=6889476&loc=d3e330036-122817

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 289
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 45
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section I
-Subsection 7

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Regulatory Matters - Regulatory Assets and Liabilities (Details) - USD ($)
$ in Millions

Dec. 31, 2012

Dec. 31, 2011

Regulatory Assets and Liabilities [Line Items]

Current Regulatory Asset

$ 22.5

$ 17.5

Non-Current Regulatory Asset

340.3

345.9

Total Regulatory Assets

362.8

363.4

Non-Current Regulatory Liability

60.1

43.5

Income Taxes [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Liability

19.5

21.9

Plant Removal Obligations [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Liability

18.1

15.0

Wholesale and Retail Contra AFUDC [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Liability

15.5

1.5

Other [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Liability

7.0

5.1

Deferred Fuel [Member]

Regulatory Assets and Liabilities [Line Items]

Current Regulatory Asset

^[1]

22.5

17.5

Future Benefit Obligations Under Defined Benefit Pension and Other Postretirement Benefit Plans [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Asset

260.7

292.8

Income Taxes [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Asset

36.0

28.6

Asset Retirement Obligation [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Asset

12.1

9.8

Cost Recovery Riders [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Asset

^[2]

18.5

0.7

PPACA Income Tax Deferral [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Asset

5.0

Conservation Improvement Program [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Asset

4.3

4.6

Other [Member]

Regulatory Assets and Liabilities [Line Items]

Non-Current Regulatory Asset

$ 3.7

$ 4.4

[1]	Current regulatory assets are included in prepayments and other on our Consolidated Balance Sheet.
[2]	The increase in cost recovery rider regulatory assets in 2012 is primarily due to revenues related to our Bison Wind Energy Center.

Investment in ATC (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Investment in ATC (Details) - USD ($) $ in Millions	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Balance Sheet Data [Abstract]
Current Assets		$ 63.1	$ 58.7
Non-Current Assets		3,274.7	3,053.7
Total Assets		3,337.8	3,112.4
Current Liabilities		251.5	298.5
Long-Term Debt		1,550.0	1,400.0
Other Non-Current Liabilities		95.8	82.6
Members' Equity		1,440.5	1,331.3
Total Liabilities and Members' Equity		3,337.8	3,112.4
Income Statement Data [Abstract]
Revenue		603.2	567.2	$ 556.7
Operating Expense		281.0	261.6	251.1
Other Expense		84.8	81.7	85.9
Net Income		237.4	223.9	219.7
ALLETE's Equity in Net Income		$ 19.4	18.4	17.9
Investment in ATC [Abstract]
Equity Method Investment, Ownership Percentage		8.00%
Equity Method Investment, Approved Return on Common Equity		12.20%
Equity Method Investment, Expected Future Investment		$ 2.0
ALLETE's Investment in ATC [Roll Forward]
Equity Investment Beginning Balance	$ 107.3	98.9	93.3
Cash Investments	$ 0.4	4.7	2.0
Equity Earnings in ATC		19.4	18.4	17.9
Distributed ATC Earnings		(15.7)	(14.8)
Equity Investment Ending Balance		$ 107.3	$ 98.9	$ 93.3

Investments (Details) - USD ($) $ in Millions	12 Months Ended
Investments (Details) - USD ($) $ in Millions	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 05, 2011
Available-for-sale Securities [Abstract]
Cost	$ 27.4	$ 27.3	$ 27.4
Gross Unrealized Gain	0.5	0.1	0.2
Gross Unrealized (Loss)	(1.1)	(2.7)	(2.4)
Fair Value	26.8	24.7	25.2
Net Proceeds	1.5	7.8	0.6
Gross Realized Gain	0.0	0.0	0.0
Gross Realized (Loss)	0.0	0.0	0.0
Net Unrealized Gain (Loss) in Other Comprehensive Income	1.2	(0.3)	0.8
Available for sale securities, Issued by States of the United States (ARS)				$ 6.7
Investments [Abstract]
ALLETE Properties	91.1	91.3
Available-for-sale Securities	26.8	24.7
Other	25.6	16.3
Total Investments	143.5	132.3
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Land Inventory Beginning Balance	86.0	86.0
Deeds to Collateralized Property	0.5	1.8
Land Impairment	0.0	(1.7)
Cost of Sales	(0.2)	(0.3)
Capitalized Improvements and Other	0.2	0.2
Land Inventory Ending Balance	86.5	86.0	$ 86.0
Long-Term Finance Receivables (net of allowances of $0.6 and $0.6)	1.4	2.0
Other	3.2	3.3
Total Real Estate Assets	91.1	91.3
Long-Term Finance Receivables, Allowance	$ 0.6	$ 0.6

Investments Parenthetical (Details) - USD ($) $ in Millions	Dec. 31, 2012	Dec. 31, 2011
Investments Parenthetical [Abstract]
Long-Term Finance Receivables, Allowance	$ 0.6	$ 0.6

Derivatives - Hedged Items (Details) - Term Loan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Sep. 30, 2011
Debt Instrument [Line Items]
Term Loan Principal Amount		$ 75.0
Term Loan Variable Rate Basis	one-month LIBOR
Term Loan Basis Spread on Variable Rate	1.00%

Derivatives (Details) - Interest Rate Swap [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Derivative [Line Items]
Percentage of Debt Hedged by Interest Rate Swap	8.00%
Interest Rate Swap Variable Rate Basis	one-month LIBOR
Interest Rate Swap Fixed Interest Rate	0.825%
Discussion of Interest Rate Cash Flow Hedge Effectiveness Assessment and Measurement	The shortcut method is used to assess hedge effectiveness. At inception, all shortcut method requirements were satisfied; thus changes in value of the Swap designated as the hedging instrument will be deemed 100 percent effective. As a result, there was no ineffectiveness recorded for the year ended December 31, 2012.
Interest Rate Swap Liability	$ (0.7)	$ (0.4)

Fair Value - Recurring Fair Value Measures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Liabilities [Abstract]
Fair Value Activity in Level 3	$ 0.0
Fair Value Hierarchy Transfers, All Levels	0.0	$ 0.0
Recurring Fair Value Measures [Member]
Investments [Abstract]
Available-for-sale Securities - Equity Securities	18.0	17.6
Available-for-sale Securities - Corporate Debt Securities	8.8	8.2
Cash Equivalents	20.7	11.4
Total Fair Value of Assets	47.5	37.2
Liabilities [Abstract]
Deferred Compensation	14.0	12.8
Derivatives - Interest Rate Swap	0.7	0.4
Total Fair Value of Liabilities	14.7	13.2
Total Net Fair Value of Assets (Liabilities)	32.8	24.0
Recurring Fair Value Measures [Member] \| Level 1 [Member]
Investments [Abstract]
Available-for-sale Securities - Equity Securities	18.0	17.6
Available-for-sale Securities - Corporate Debt Securities	0.0	0.0
Cash Equivalents	20.7	11.4
Total Fair Value of Assets	38.7	29.0
Liabilities [Abstract]
Deferred Compensation	0.0	0.0
Derivatives - Interest Rate Swap	0.0	0.0
Total Fair Value of Liabilities	0.0	0.0
Total Net Fair Value of Assets (Liabilities)	38.7	29.0
Recurring Fair Value Measures [Member] \| Level 2 [Member]
Investments [Abstract]
Available-for-sale Securities - Equity Securities	0.0	0.0
Available-for-sale Securities - Corporate Debt Securities	8.8	8.2
Cash Equivalents	0.0	0.0
Total Fair Value of Assets	8.8	8.2
Liabilities [Abstract]
Deferred Compensation	14.0	12.8
Derivatives - Interest Rate Swap	0.7	0.4
Total Fair Value of Liabilities	14.7	13.2
Total Net Fair Value of Assets (Liabilities)	(5.9)	(5.0)
Recurring Fair Value Measures [Member] \| Level 3 [Member]
Investments [Abstract]
Available-for-sale Securities - Equity Securities	0.0	0.0
Available-for-sale Securities - Corporate Debt Securities	0.0	0.0
Cash Equivalents	0.0	0.0
Total Fair Value of Assets	0.0	0.0
Liabilities [Abstract]
Deferred Compensation	0.0	0.0
Derivatives - Interest Rate Swap	0.0	0.0
Total Fair Value of Liabilities	0.0	0.0
Total Net Fair Value of Assets (Liabilities)	$ 0.0	$ 0.0

Fair Value - Recurring Fair Value Measures, Activity in Level 3 (Details) - Debt Securities Issued by States of the United States (ARS) [Member]
$ in Millions

12 Months Ended

Dec. 31, 2011

USD ($)

Recurring Fair Value Measures, Activity in Level 3 [Line Items]

Beginning Balance

$ 6.7

Redeemed During the Period

(6.7)

^[1]

Ending Balance

$ 0.0

[1]	The ARS were redeemed at carrying value on January 5, 2011.

Fair Value - Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2012	Dec. 31, 2011
Financial Instruments [Abstract]
Long-Term Debt, Including Current Portion - Carrying Amount	$ 1,018.1	$ 863.3
Long-Term Debt, Including Current Portion - Fair Value	$ 1,143.7	$ 966.4

Short-Term and Long-Term Debt (Details) $ in Millions	12 Months Ended
Short-Term and Long-Term Debt (Details) $ in Millions	Dec. 31, 2012 USD ($)	Jun. 30, 2012 USD ($)	Feb. 01, 2012 USD ($)	Dec. 31, 2011 USD ($)
Financial Covenants [Abstract]
Required Indebtedness to Total Capital Ratio	0.65
Actual Indebtedness to Total Capital Ratio	0.46
Maturities of Long-term Debt [Abstract]
Long-Term Debt	$ 933.6			$ 857.9
Long-Term Debt Due Within One Year	84.5			5.4
Long-Term Debt, 2014 Maturities	94.8
Long-Term Debt, 2015 Maturities	17.4
Long-Term Debt, 2016 Maturities	21.7
Long-Term Debt, 2017 Maturities	51.2
Long-Term Debt, Thereafter Maturities	748.5
Debt Instrument [Line Items]
Short-Term Debt	84.5			6.5
Letter of Credit Maximum Issuances	50.0
Lines of Credit, Current	0.0			1.1
Proceeds from Issuance of First Mortgage Bond	160.0
Lines of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	406.4			$ 256.4
ALLETE LOC January 2014 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	150.0		$ 150.0
Letter of Credit Maximum Issuances			$ 10.0
Line of Credit Facility, Amount Outstanding		$ 14.0
ALLETE LOC June 2015 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	250.0
ALLETE Bonds 4.86% Due 2013 [Member]
Maturities of Long-term Debt [Abstract]
Long-Term Debt Due Within One Year	60.0
ALLETE Bonds 3.20% Due July 2026 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of First Mortgage Bond	$ 75.0
First Mortgage Bonds, Interest Rate	3.20%
ALLETE Bonds 4.08% Due July2042 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of First Mortgage Bond	$ 85.0
First Mortgage Bonds, Interest Rate	4.08%
Industrial Development Revenue Bonds 6.5% Due 2025 [Member]
Debt Instrument [Line Items]
First Mortgage Bonds, Interest Rate	6.50%
Redemption of Bond	$ 6.0

Short-term and Long-term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term Debt	$ 1,018.1	$ 863.3
Less: Due Within One Year	84.5	5.4
Net Long-Term Debt	933.6	857.9
4.86% Series Due 2013 [Member]
Debt Instrument [Line Items]
Long-term Debt	60.0	60.0
Less: Due Within One Year	60.0
6.94% Series Due 2014 [Member]
Debt Instrument [Line Items]
Long-term Debt	18.0	18.0
7.70% Series Due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt	20.0	20.0
8.17% Series Due 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt	42.0	42.0
5.28% Series Due 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt	35.0	35.0
4.85% Series Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt	15.0	15.0
4.95% Pollution Control Series F Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt	111.0	111.0
6.02% Series Due 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt	75.0	75.0
4.90% Series Due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt	30.0	30.0
5.10% Series Due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt	30.0	30.0
3.20% Series Due 2026 [Member]
Debt Instrument [Line Items]
Long-term Debt	75.0	0.0
5.99% Series Due 2027 [Member]
Debt Instrument [Line Items]
Long-term Debt	60.0	60.0
5.69% Series Due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt	50.0	50.0
6.00% Series Due 2040 [Member]
Debt Instrument [Line Items]
Long-term Debt	35.0	35.0
5.82% Series Due 2040 [Member]
Debt Instrument [Line Items]
Long-term Debt	45.0	45.0
4.08% Series Due 2042 [Member]
Debt Instrument [Line Items]
Long-term Debt	85.0	0.0
SWL&P First Mortgage Bonds 7.25% Series Due 2013 [Member]
Debt Instrument [Line Items]
Long-term Debt	10.0	10.0
Senior Unsecured Notes 5.99% Due 2017 [Member]
Debt Instrument [Line Items]
Long-term Debt	50.0	50.0
Variable Demand Revenue Refunding Bonds Series 1997 A, B, and C Due 2013-2020 [Member]
Debt Instrument [Line Items]
Long-term Debt	27.5	28.2
Industrial Development Revenue Bonds 6.5% Due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt	0.0	6.0
Industrial Development Variable Rate Demand Refunding Revenue Bonds Series 2006 Due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt	27.8	27.8
Unsecured Term Loan Variable Rate Due 2014 [Member]
Debt Instrument [Line Items]
Long-term Debt	75.0	75.0
Other Long-Term Debt, 1.0%-8.0% Due 2013-2037 [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 41.8	$ 40.3

Commitments, Guarantees and Contingencies - Power Purchase Agreements (Details) $ in Millions	12 Months Ended
	Dec. 31, 2012 USD ($) MWh Years kV MW	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)
Square Butte PPA [Member]
Power Purchase Agreements [Line Items]
Generating Unit Capacity (MW) \| MW	455
Output Entitlement	50.00%
PPA Counterparty Debt Outstanding \| $	$ 416.9
Annual Debt Service \| $	44.0
Power Purchased under Long-term Contracts \| $	67.1	$ 61.2	$ 55.2
Interest Expense \| $	$ 11.1	$ 11.1	$ 10.2
Minnkota PPA [Member]
Power Purchase Agreements [Line Items]
Output Being Purchased (MW) \| MW	50
Oliver Wind I PPA [Member]
Power Purchase Agreements [Line Items]
Output Being Purchased (MW) \| MW	50
Term of Contract (Years) \| Years	25
Fixed Capacity Charges \| $	$ 0.0
Oliver Wind II PPA [Member]
Power Purchase Agreements [Line Items]
Output Being Purchased (MW) \| MW	48
Term of Contract (Years) \| Years	25
Fixed Capacity Charges \| $	$ 0.0
Manitoba Hydro PPA (expires April 2015) [Member]
Power Purchase Agreements [Line Items]
Output Being Purchased (MW) \| MW	50
Manitoba Hydro PPA (expires April 2022) [Member]
Power Purchase Agreements [Line Items]
Output Being Purchased (MWh) \| MWh	1,000,000
Manitoba Hydro PPA (expires 2035) [Member]
Power Purchase Agreements [Line Items]
Output Being Purchased (MW) \| MW	250
Term of Contract (Years) \| Years	15
Transmission Line Capacity (kV) \| kV	500

Commitments, Guarantees and Contingencies - North Dakota Wind Development (Details) $ in Millions	Dec. 31, 2012 USD ($) Miles kV MW
DC Transmission Line from Square Butte [Member]
North Dakota Wind Development [Line Items]
Transmission Line Length (Miles) \| Miles	465
Transmission Line Capacity (kV) \| kV	250
Bison Wind Energy Center [Member]
North Dakota Wind Development [Line Items]
Generating Unit Capacity (MW)	292
Bison 1 [Member]
North Dakota Wind Development [Line Items]
Transmission Line Length (Miles) \| Miles	22
Transmission Line Capacity (kV) \| kV	230
Generating Unit Capacity (MW)	82
Capital Cost Spent to Date \| $	$ 174.9
Bison 2 [Member]
North Dakota Wind Development [Line Items]
Generating Unit Capacity (MW)	105
Capital Cost Spent to Date \| $	$ 148.6
Bison 3 [Member]
North Dakota Wind Development [Line Items]
Generating Unit Capacity (MW)	105
Capital Cost Spent to Date \| $	$ 149.8

Commitments, Guarantees and Contingencies - Coal Rail and Shipping Contracts (Details) - Coal and Transportation [Member] $ in Millions	Dec. 31, 2012 USD ($)
Coal Rail and Shipping Contracts [Line Items]
Coal Supply and Transportation Agreements, Minimum Annual Payment Obligation in 2013	$ 51.4
Coal Supply and Transportation Agreements, Minimum Annual Payment Obligation in 2014	$ 0.8

Commitments, Guarantees and Contingencies - Leasing Agreements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Leasing Agreements [Line Items]
Operating Leases, Future Minimum Payments, Current	$ 11.5
Operating Leases, Future Minimum Payments, Due in Two Years	11.7
Operating Leases, Future Minimum Payments, Due in Three Years	11.4
Operating Leases, Future Minimum Payments, Due in Four Years	9.3
Operating Leases, Future Minimum Payments, Due in Five Years	8.5
Operating Leases, Future Minimum Payments, Due Thereafter	35.0
Operating Leases, Rent Expense	11.5	$ 9.4	$ 9.4
BNI Dragline [Member]
Leasing Agreements [Line Items]
Termination Fee	3.0
Operating Leases, Future Minimum Payments, Current	$ 2.8

Commitments, Guarantees and Contingencies - Transmission (Details) $ in Millions	Dec. 31, 2012 USD ($) Miles kV	Dec. 31, 2011 USD ($)
CapX2020 [Member]
Transmission [Line Items]
Number of Projects	3
Minimum Amount Expected to be Invested in Transmission Projects	$ 100.0
Maximum Amount Expected to be Invested in Transmission Projects	110.0
Capital Cost Spent to Date	$ 48.2	$ 27.8
CapX2020 Fargo to Monticello Project [Member]
Transmission [Line Items]
Transmission Line Length (Miles) \| Miles	238
Transmission Line Capacity (kV) \| kV	345
Capital Cost Spent to Date	$ 37.3	20.4
CapX2020 Monticello to St. Cloud Project [Member]
Transmission [Line Items]
Transmission Line Length (Miles) \| Miles	28
Transmission Line Capacity (kV) \| kV	345
CapX2020 Bemidji to Grand Rapids Project [Member]
Transmission [Line Items]
Transmission Line Length (Miles) \| Miles	70
Transmission Line Capacity (kV) \| kV	230
Capital Cost Spent to Date	$ 10.9	$ 7.4

Commitments, Guarantees and Contingencies - Environmental Matters (Details) - Boswell Unit 4 [Member] $ in Millions	Dec. 31, 2012 USD ($)
Schedule of Utility Generating Facilities [Line Items]
Estimated Environmental Compliance Costs - Minimum	$ 350
Estimated Environmental Compliance Costs - Maximum	$ 400

Commitments, Guarantees and Contingencies - Other Matters (Details) $ in Millions	12 Months Ended
	Dec. 31, 2012 USD ($) Years	Dec. 31, 2011
BNI Coal Reclamation Liability [Member]
Guarantor Obligations [Line Items]
Surety Bond	$ 29.8
Letters of Credit	2.6
Estimated Reclamation Liability	32.4
ALLETE Properties Performance and Maintenance Obligations [Member]
Guarantor Obligations [Line Items]
Surety Bond	10.2
Performance and Maintenance Obligations	7.4
Performance and Maintenance Obligations, Land Purchaser Contractual Obligation	0.6
Town Center Community Development District Obligation [Member]
Guarantor Obligations [Line Items]
Community Development District Obligation, Bond	$ 26.4
Community Development Distrcit Obligation, Bond Interest Rate	6.00%
Community Development District Obligation, Bond Term (in Years) \| Years	31
Community Development District Obligation, Ownership Percentage of Benefited Property	73.00%	73.00%
Community Development District Obligation, Annual Assessment	$ 1.4
Palm Coast Park Community Development District Obligation [Member]
Guarantor Obligations [Line Items]
Community Development District Obligation, Bond	$ 31.8
Community Development Distrcit Obligation, Bond Interest Rate	5.70%
Community Development District Obligation, Bond Term (in Years) \| Years	31
Community Development District Obligation, Ownership Percentage of Benefited Property	93.00%	93.00%
Community Development District Obligation, Annual Assessment	$ 2.1

Commitments, Guarantees and Contingencies - Legal Proceedings (Details) $ in Millions	12 Months Ended
	Dec. 31, 2012 USD ($)
Pending Litigation [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	$ 20.0

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14557-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 11
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 12
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Common Stock and Earnings Per Share - Summary of Common Stock (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Class of Stock [Line Items]
Common Stock Outstanding, Shares		39,400	37,500
Purchase of Non-Controlling Interest, Shares	200
Contributions to Pension, Value		$ 0.0	$ (20.0)	$ 0.0
Common Stock [Member]
Class of Stock [Line Items]
Common Stock Outstanding, Shares		39,377	37,513	35,817	35,221
Common Stock Outstanding, Value		$ 784.7	$ 705.6	$ 636.1	$ 613.4
Employee Stock Purchase Program, Shares		20	20	19
Employee Stock Purchase Program, Value		$ 0.8	$ 0.8	$ 0.6
Invest Direct, Shares		474	437	346
Invest Direct, Value		$ 19.2	$ 17.2	$ 11.7
Options and Stock Awards, Shares		95	109	51
Options and Stock Awards, Value		$ 6.0	$ 6.7	$ 4.4
Equity Issuance Program, Shares		1,275	400	180
Equity Issuance Program, Value		$ 53.1	$ 16.0	$ 6.0
Purchase of Non-Controlling Interest, Shares			222
Purchase of Non-Controlling Interest, Value			$ 8.8
Contributions to Pension, Shares			508
Contributions to Pension, Value			$ 20.0
Antidilutive Options to Purchase Shares of Common Stock Excluded from the Computation of Earnings Per Share		200	300	500
Equity Issuance Program Shares Authorized		9,600
Equity Issuance Program Shares Available for Issuance		4,500

Common Stock and Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share - Basic [Abstract]
Net Income Attributable to ALLETE	$ 28.9	$ 29.4	$ 14.4	$ 24.4	$ 19.1	$ 20.5	$ 17.0	$ 37.2	$ 97.1	$ 93.8	$ 75.3
Average Common Shares									37.6	35.3	34.2
Earnings Per Share	$ 0.76	$ 0.78	$ 0.39	$ 0.66	$ 0.53	$ 0.57	$ 0.49	$ 1.07	$ 2.59	$ 2.66	$ 2.20
Earnings Per Share - Diluted [Abstract]
Net Income Attributable to ALLETE									$ 97.1	$ 93.8	$ 75.3
Average Common Shares									37.6	35.4	34.3
Earnings Per Share	$ 0.75	$ 0.78	$ 0.39	$ 0.66	$ 0.53	$ 0.57	$ 0.48	$ 1.07	$ 2.58	$ 2.65	$ 2.19
Dilutive Securities (Shares)									0.0	0.1	0.1

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.21)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=16381557&loc=d3e4984-109258

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1252-109256

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.23)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 18
-Article 7

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 36, 37, 38
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 20
-Article 5

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 21
-Article 9

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References + Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Net Income
-URI http://asc.fasb.org/extlink&oid=6518256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.18)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.22)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=6519514

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e565-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 10, 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph A7
-Appendix A

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 87-21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28, 29, 30
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 20
-Article 9

+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References + Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1448-109256

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Weighted-Average Number of Common Shares Outstanding
-URI http://asc.fasb.org/extlink&oid=6528421

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 8
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Other Income (Expense) (Details) - USD ($) $ in Millions	12 Months Ended
Other Income (Expense) (Details) - USD ($) $ in Millions	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other Income (Expense) [Abstract]
AFUDC - Equity	$ 5.1	$ 2.5	$ 4.2
Investment and Other Income	0.9	1.9	0.4
Total Other Income	$ 6.0	$ 4.4	$ 4.6

Income Tax Expense (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Jun. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Income Tax Expense [Abstract]

Current Federal Tax Expense (Benefit)

^[1]

$ 0.0

$ 1.4

$ (23.0)

Current State Tax Expense (Benefit)

^[1]

0.5

(1.6)

1.3

Total Current Tax Expense (Benefit)

0.5

(0.2)

(21.7)

Deferred Federal Tax Expense

^[2]

38.1

27.3

61.4

Deferred State Tax Expense (Benefit)

^[2]

(1.7)

9.5

5.3

Change in Valuation Allowance

^[3]

2.0

(0.1)

0.2

Investment Tax Credit Amortization

(0.9)

Total Deferred Tax Expense

37.5

35.8

66.0

Total Income Tax Expense

38.0

35.6

44.3

2010 Rate Case Stipulation Agreement, Revenue Receivable Foregone [Member]

Income Tax Expense [Abstract]

Total Deferred Tax Expense

0.0

(6.2)

0.0

PPACA Elimination of Medicare Part D [Member]

Income Tax Expense [Abstract]

Total Deferred Tax Expense

$ 2.9

0.0

(2.9)

0.0

Unusual or Infrequent Item [Line Items]

Tax Adjustments, Settlements, and Unusual Provisions

$ 0.0

$ 4.0

[1]	For the years ended December 31, 2012 and 2011, the federal and state current tax expense (benefit) was due to NOLs which resulted primarily from the bonus depreciation provision of the Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010. The 2012 and 2011 federal and state NOLs will be carried forward to offset future taxable income. For the year ended December 31, 2010, a federal current tax benefit was recorded as a result of tax planning initiatives and the bonus depreciation provision in the Small Business Jobs Act of 2010. The 2010 federal NOL was partially utilized by carrying it back against prior years’ income with the remainder carried forward to offset future years’ income.
[2]	For the year ended December 31, 2012, the state deferred tax benefit of $1.7 million is due to state renewable tax credits earned which will be carried forward to offset future state income tax expense. The year ended December 31, 2011, included an income tax benefit for the reversal of a $6.2 million deferred tax liability related to a revenue receivable that Minnesota Power agreed to forgo as part of a stipulation and settlement agreement in its 2010 rate case and a benefit of $2.9 million related to the MPUC approval of our request to defer the retail portion of the tax charge taken in 2010 as a result of the PPACA. Included in the year ended December 31, 2010, was a charge of $4.0 million as a result of the PPACA. (See Note 5. Regulatory Matters.)
[3]	For the year ending December 31, 2012, the change in the valuation allowance is due to state renewable tax credits earned in 2012 which are not expected to be utilized within their allowable tax carryforward period.

Income Tax Expense - Reconciliation of Taxes from Federal Statutory Rate to Total Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Expense [Abstract]
Income Before Non-Controlling Interest and Income Taxes		$ 135.1	$ 129.2	$ 119.1
Statutory Federal Income Tax Rate		35.00%	35.00%	35.00%
Income Taxes Computed at 35 Percent Statutory Federal Rate		$ 47.3	$ 45.2	$ 41.7
Increase (Decrease) in Tax [Abstract]
State Income Taxes - Net of Federal Income Tax Benefit		1.2	6.0	4.5
Unusual or Infrequent Item [Line Items]
Deferred Income Tax Expense (Benefit)		37.5	35.8	66.0
Regulatory Differences for Utility Plant		(2.2)	(1.2)	(2.0)
Production Tax Credits		7.6	4.3	1.6
Other		(0.7)	(1.0)	(2.3)
Income Tax Expense		$ 38.0	$ 35.6	$ 44.3
Effective Income Tax Rate		28.10%	27.60%	37.20%
PPACA Elimination of Medicare Part D [Member]
Unusual or Infrequent Item [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions		$ 0.0	$ 0.0	$ 4.0
Deferred Income Tax Expense (Benefit)	$ 2.9	0.0	(2.9)	0.0
2010 Rate Case Stipulation Agreement [Member]
Unusual or Infrequent Item [Line Items]
Deferred Income Tax Expense (Benefit)		$ 0.0	$ (6.2)	$ 0.0

Income Tax Expense - Deferred Tax Assets and Liabilities (Details) - USD ($)
$ in Millions

Dec. 31, 2012

Dec. 31, 2011

Deferred Tax Assets [Abstract]

Employee Benefits and Compensation

$ 120.2

$ 132.7

Property Related

59.8

56.4

NOL Carryforwards

90.8

61.7

Tax Credit Carryforwards

28.3

12.2

Other

24.6

20.4

Gross Deferred Tax Assets

323.7

283.4

Deferred Tax Asset Valuation Allowance

(2.4)

(0.4)

Total Deferred Tax Assets

321.3

283.0

Deferred Tax Liabilities [Abstract]

Property Related

577.1

482.7

Regulatory Asset for Benefit Obligations

104.3

117.9

Unamortized Investment Tax Credits

11.9

12.8

Partnership Basis Differences

28.6

24.4

Other

30.1

24.0

Total Deferred Tax Liabilities

752.0

661.8

Net Deferred Income Taxes

430.7

378.8

Net Current Deferred Tax Liabilities

^[1]

6.9

5.2

Net Long-Term Deferred Tax Liabilities

$ 423.8

$ 373.6

[1]	Included in Other Current Liabilities.

Income Tax Expense - NOL and Tax Credit Carryforwards (Details) - USD ($)

Dec. 31, 2012

Dec. 31, 2011

Federal [Member]

NOL and Tax Credit Carryforwards [Line Items]

NOL Carryforward

^[1]

$ 244,100,000

$ 162,000,000

Tax Credit Carryforwards

16,000,000

8,400,000

NOL and Tax Credit Carryforwards, Valuation Allowance

State [Member]

NOL and Tax Credit Carryforwards [Line Items]

NOL Carryforward

^[1],[2]

90,600,000

73,100,000

Tax Credit Carryforwards

^[3]

10,300,000

$ 3,800,000

NOL Carryforwards, Valuation Allowance

400,000

Tax Credit Carryforwards, Valuation Allowance

$ 2,000,000

[1]	Pretax amounts
[2]	Net of $0.4 million valuation allowance.
[3]	Net of $2.0 million valuation allowance.

- Definition

The portion of the valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from net operating loss carryforwards for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 30
-Paragraph 5
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=6907311&loc=d3e30536-109315

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 48
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 43
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 17
-Subparagraph e
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The portion of the deferred tax asset arising from a tax credit carryforward for which it is more likely than not that a tax benefit will not be realized.

+ References + Details

Income Tax Expense - Gross Unrecognized Income Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Gross Unrecognized Income Tax Benefits [Roll Forward]
Balance at January 1	$ 11.4	$ 12.3	$ 9.5
Reductions for Tax Positions Related to the Current Year	0.0	0.0	(0.2)
Additions for Tax Positions Related to Prior Years	0.0	0.0	4.4
Reduction for Tax Positions Related to Prior Years	(8.7)	(0.9)	0.0
Reductions for Settlements	0.0	0.0	(0.3)
Reductions for Expired Statute of Limitations	0.0	0.0	(1.1)
Balance as of December 31	2.7	11.4	12.3
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	0.5
Unrecognized Tax Benefits, Accrued Interest	0.5	1.1	0.7
Unrecognized Tax Benefits, Penalties	0.0	0.0	0.0
Unrecognized Tax Benefits, Interest Expense (Reduction)	(0.6)	$ 0.4	$ (0.2)
Reasonably Possible Change in Unrecognized Tax Benefits in Next 12 Months	$ 2.5

Pension and Other Postretirement Benefit Plans - Contributions (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Feb. 15, 2013
Pension and Other Postretirement Benefit Plans [Abstract]
Defined Contribution Plan, Employer Matching Contribution, Amount		$ 7.7	$ 7.3
Defined Benefit Plan Disclosure [Line Items]
ALLETE Common Stock Contributed to Pension Plan		0.0	(20.0)	$ 0.0
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Employer Contributions		7.3	33.8
ALLETE Common Stock Contributed to Pension Plan			20.0
Defined Benefit Plans, Estimated Employer Contributions		0.0
Postretirement Health and Life [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Employer Contributions	$ 4.8
Defined Benefit Plans, Estimated Employer Contributions					$ 0.0
VEBA [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Employer Contributions	2.8	1.5	10.9
Grantor Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Employer Contributions	$ 2.0	$ 0.0	$ 0.0

Pension and Other Postretirement Benefit Plans - Obligation and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Change in Plan Assets [Roll Forward]
Non-Current Liabilities	$ 228.2	$ 253.5
Other Investments, Grantor Trust	143.5	132.3
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation	598.7	550.6
Change in Benefit Obligation [Roll Forward]
Obligation, Beginning of Year	597.5	525.6
Service Cost	9.1	7.6	$ 6.2
Interest Cost	26.4	27.4	26.2
Actuarial Loss (Gain)	38.5	54.6
Benefits Paid	(30.9)	(28.6)
Participant Contributions	11.5	10.9
Obligation, End of Year	652.1	597.5	525.6
Change in Plan Assets [Roll Forward]
Fair Value, Beginning of Year	432.4	382.0
Actual Return on Plan Assets	38.7	33.2
Employer Contribution	19.9	45.8
Participant Contributions	11.5	10.9
Benefits Paid	(30.9)	(28.6)
Fair Value, End of Year	460.1	432.4	382.0
Funded Status, End of Year	(192.0)	(165.1)
Current Liabilities	(1.1)	(1.1)
Non-Current Liabilities	(190.9)	(164.0)
Postretirement Health and Life [Member]
Change in Benefit Obligation [Roll Forward]
Obligation, Beginning of Year	210.6	204.1
Service Cost	4.2	3.8	4.8
Interest Cost	9.4	10.8	10.9
Actuarial Loss (Gain)	(43.2)	(2.9)
Benefits Paid	(9.5)	(7.7)
Participant Contributions	2.6	2.5
Plan Amendments	(5.3)	0.0
Obligation, End of Year	168.8	210.6	204.1
Change in Plan Assets [Roll Forward]
Fair Value, Beginning of Year	121.0	114.7
Actual Return on Plan Assets	14.3	0.0
Employer Contribution	2.3	11.4
Participant Contributions	2.6	2.5
Participant Contributions, Excluding Key Employees	2.5	2.5
Benefits Paid	(9.5)	(7.7)
Benefits Paid, Excluding Key Employees	(9.1)	(7.6)
Fair Value, End of Year	131.0	121.0	$ 114.7
Funded Status, End of Year	(37.8)	(89.6)
Current Liabilities	(0.8)	(0.9)
Non-Current Liabilities	(37.0)	(88.7)
Grantor Trust [Member]
Change in Plan Assets [Roll Forward]
Other Investments, Grantor Trust	$ 22.1	$ 20.3

Pension and Other Postretirement Benefit Plans - Unrecognized Costs (Details) - USD ($) $ in Millions	Dec. 31, 2012	Dec. 31, 2011
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net Loss	$ 286.8	$ 269.0
Prior Service Cost (Credit)	0.7	1.1
Total Unrecognized Costs	287.5	270.1
Postretirement Health and Life [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net Loss	23.5	78.5
Prior Service Cost (Credit)	(13.1)	(9.5)
Transition Obligation	0.0	0.1
Total Unrecognized Costs	$ 10.4	$ 69.1

- Definition

The total of net gain (loss), prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (j-k)
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e681-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669686-108580

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 26
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 7
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph i
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.

+ References + Details

- Definition

Amount related to the pretax cost of benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Glossary Prior Service Cost
-URI http://asc.fasb.org/extlink&oid=6521920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Glossary Prior Service Cost
-URI http://asc.fasb.org/extlink&oid=6521884

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 7
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph i
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Before tax amount of net transition assets (obligations) which has yet to be recognized as a component of net periodic benefit cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (i)-(j)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Transition Asset
-URI http://asc.fasb.org/extlink&oid=6749452

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Transition Obligation
-URI http://asc.fasb.org/extlink&oid=6749492

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (k)
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 7
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph i
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph ii
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Pension and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service Cost	$ 9.1	$ 7.6	$ 6.2
Interest Cost	26.4	27.4	26.2
Expected Return on Plan Assets	(35.4)	(34.6)	(33.7)
Amortization of Loss	17.5	12.1	6.6
Amortization of Prior Service Cost (Credit)	0.3	0.3	0.5
Net Expense	17.9	12.8	5.8
Postretirement Health and Life [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service Cost	4.2	3.8	4.8
Interest Cost	9.4	10.8	10.9
Expected Return on Plan Assets	(9.9)	(9.7)	(9.5)
Amortization of Loss	7.5	8.5	4.8
Amortization of Prior Service Cost (Credit)	(1.7)	(1.7)	(0.1)
Amortization of Transition Obligation	0.1	0.1	2.5
Net Expense	$ 9.6	$ 11.8	$ 13.4

Pension and Other Postretirement Benefit Plans - Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income and Regulatory Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net (Gain) Loss	$ 35.2	$ 56.1
Amortization of Prior Service (Cost) Credit	(0.3)	(0.3)
Amortization of Loss	(17.5)	(12.2)
Total Recognized in Other Comprehensive Income and Regulatory Assets	17.4	43.6
Postretirement Health and Life [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net (Gain) Loss	(47.5)	6.9
Prior Service Credit Arising During the Period	(5.3)	0.0
Amortization of Prior Service (Cost) Credit	1.7	1.7
Amortization of Transition Obligation	(0.1)	(0.1)
Amortization of Loss	(7.5)	(8.5)
Total Recognized in Other Comprehensive Income and Regulatory Assets	$ (58.7)	$ 0.0

- Definition

Before tax amount of the benefit improvement costs resulting from a plan amendment that occurred that has not been recognized in net periodic benefit cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph i
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 130
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 4
-Subparagraph c, d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 37
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 7
-Subparagraph a
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Before tax amount of the income statement impact of the reclassification adjustment for prior service costs recognized as a component of net period benefit cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 17, 19, 24
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 4
-Subparagraph c, d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph i
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Pension and Other Postretirement Benefit Plans - Information for Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets (Details) - Pension [Member] - USD ($) $ in Millions	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Projected Benefit Obligation	$ 652.1	$ 597.5
Accumulated Benefit Obligation	598.7	550.6
Fair Value of Plan Assets	$ 460.1	$ 432.4

Pension and Other Postretirement Benefit Plans - Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2012 USD ($)
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
2013	$ 31.2
2014	32.1
2015	33.2
2016	34.4
2017	35.5
Years 2018 - 2022	189.4
Postretirement Health and Life [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
2013	7.6
2014	8.2
2015	8.9
2016	9.4
2017	9.7
Years 2018 - 2022	$ 52.0

Pension and Other Postretirement Benefit Plans - Costs Recorded in Other Long-Term Assets and AOCI Expected to be Recognized as a Component of Net Pension and Postretirement Benefit Costs in the Next Fiscal Year (Details) $ in Millions	12 Months Ended
	Dec. 31, 2013 USD ($)
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net Loss	$ 21.4
Prior Service Cost (Credit)	0.3
Total Pension and Postretirement Health and Life Cost (Credit)	21.7
Postretirement Health and Life [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net Loss	1.6
Prior Service Cost (Credit)	(2.5)
Total Pension and Postretirement Health and Life Cost (Credit)	$ (0.9)

Pension and Other Postretirement Benefit Plans - Weighted-Average Assumptions Used to Determine Benefit Obligation and Net Periodic Benefit Costs (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension [Member]
Weighted-Average Assumptions Used to Determine Benefit Obligation [Abstract]
Discount Rate	4.10%	4.54%
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Discount Rate	4.54%	5.36%	5.81%
Expected Long-term Return on Plan Assets	8.25%	8.50%	8.50%
Pension [Member] \| Minimum [Member]
Weighted-Average Assumptions Used to Determine Benefit Obligation [Abstract]
Rate of Compensation Increase	4.30%	4.30%
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Rate of Compensation Increase	4.30%	4.30%	4.30%
Pension [Member] \| Maximum [Member]
Weighted-Average Assumptions Used to Determine Benefit Obligation [Abstract]
Rate of Compensation Increase	4.60%	4.60%
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Rate of Compensation Increase	4.60%	4.60%	4.60%
Postretirement Health and Life [Member]
Weighted-Average Assumptions Used to Determine Benefit Obligation [Abstract]
Discount Rate	4.13%	4.56%
Trend Rate	9.25%	10.00%
Ultimate Trend Rate	5.00%	5.00%
Year Ultimate Trend Rate Effective	2019	2018
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Discount Rate	4.56%	5.40%	5.81%
Postretirement Health and Life [Member] \| Minimum [Member]
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Expected Long-term Return on Plan Assets	6.60%	6.80%	6.80%
Postretirement Health and Life [Member] \| Maximum [Member]
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Expected Long-term Return on Plan Assets	8.25%	8.50%	8.50%

Pension and Other Postretirement Benefit Plans - Sensitivity of a One-Percentage-Point Change in Health Care Trend Rates (Details) - Postretirement Health and Life [Member] $ in Millions	12 Months Ended
	Dec. 31, 2012 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Effect of One Percent Increase on Total of Postretirement Health and Life Service and Interest Cost	$ 2.0
Effect of One Percent Decrease on Total of Postretirement Health and Life Service and Interest Cost	(1.6)
Effect of One Percent Increase on Postretirement Health and Life Obligation	18.2
Effect of One Percent Decrease on Postretirement Health and Life Obligation	$ (15.1)

Pension and Other Postretirement Benefit Plans - Plan Asset Allocations (Details) - shares

12 Months Ended

Dec. 31, 2012

Dec. 31, 2011

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Defined Benefit Plans, Company Stock Contributed (in Shares)

500,000

Pension [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

100.00%

Defined Benefit Plans, Company Stock Contributed (in Shares)

Target Plan Asset Allocation

100.00%

Pension [Member] | Equity Securities [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

54.00%

52.00%

Target Plan Asset Allocation

52.00%

Pension [Member] | Debt Securities [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

28.00%

27.00%

Target Plan Asset Allocation

30.00%

Pension [Member] | Real Estate [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

5.00%

Target Plan Asset Allocation

9.00%

Pension [Member] | Private Equity [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

13.00%

16.00%

Target Plan Asset Allocation

9.00%

Postretirement Health and Life [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

^[1]

100.00%

Target Plan Asset Allocation

^[2]

100.00%

Postretirement Health and Life [Member] | Equity Securities [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

^[1]

56.00%

51.00%

Target Plan Asset Allocation

^[2]

48.00%

Postretirement Health and Life [Member] | Debt Securities [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

^[1]

35.00%

39.00%

Target Plan Asset Allocation

^[2]

34.00%

Postretirement Health and Life [Member] | Real Estate [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

^[1]

0.00%

Target Plan Asset Allocation

^[2]

9.00%

Postretirement Health and Life [Member] | Private Equity [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Actual Plan Asset Allocation

^[1]

9.00%

10.00%

Target Plan Asset Allocation

^[2]

9.00%

[1]	Includes VEBAs and irrevocable grantor trusts.
[2]	Includes VEBAs and irrevocable grantor trusts.

Pension and Other Postretirement Benefit Plans - Recurring Fair Value Measures, Activity in Level 3 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Pension [Member] \| Equity Securities (ARS) [Member]
Activity in Level 3 [Roll Forward]
Beginning Balance	$ 0.0	$ 6.7
Actual Return on Plan Assets		0.0
Purchases, sales and settlements, net		(6.7)
Ending Balance		0.0
Pension [Member] \| Private Equity Funds [Member]
Activity in Level 3 [Roll Forward]
Beginning Balance	69.0	50.7
Actual Return on Plan Assets	(9.7)	30.9
Purchases, sales and settlements, net	(0.4)	(12.6)
Ending Balance	58.9	69.0
Pension [Member] \| Real Estate [Member]
Activity in Level 3 [Roll Forward]
Beginning Balance	21.7	20.1
Actual Return on Plan Assets	3.4	3.5
Purchases, sales and settlements, net	(0.2)	(1.9)
Ending Balance	24.9	21.7
Postretirement Health and Life [Member] \| Private Equity Funds [Member]
Activity in Level 3 [Roll Forward]
Beginning Balance	14.0	12.4
Actual Return on Plan Assets	0.2	1.1
Purchases, sales and settlements, net	(0.7)	0.5
Ending Balance	$ 13.5	$ 14.0

Employee Stock and Incentive Plans - Employee Stock Ownership Plan (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee Stock and Incentive Plans [Abstract]
ESOP Employer Loan, Description	In 1990, the ESOP issued a $75.0 million note (term not to exceed 25 years at 10.25 percent) to use as consideration for 2.8 million shares (1.9 million shares adjusted for stock splits) of our newly issued common stock. The note was refinanced in 2006 at 6 percent.
ESOP Compensation Expense	$ 7.7	$ 7.4	$ 7.1
ESOP Shares, Allocated	2.2	2.2	2.2
ESOP Shares, Unallocated	0.7	1.0	1.3
ESOP Shares, Total	2.9	3.2	3.5
Fair Value of Unallocated ESOP Shares	$ 28.7	$ 42.0	$ 48.4

Employee Stock and Incentive Plans - Stock-Based Compensation (Details) - shares

12 Months Ended

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2009

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Grants

^[1]

Exercised

49,075

80,798

40,769

Options Outstanding

395,678

460,234

560,887

646,235

Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting Period

3 years

Restricted Stock Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting Period

3 years

Employee Stock Purchase Plan (ESPP) [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

ESPP Discount

5.00%

Executive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Common Stock Reserved

1,200,000

Shares Available for Issuance

600,000

Director Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Grants

Exercised

1,293

Options Outstanding

[1]	Stock options have not been granted since 2008. The weighted-average grant-date intrinsic value of options granted in 2008 was $6.18.

Employee Stock and Incentive Plans - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 2.1	$ 1.6	$ 2.2
Income Tax Benefit	0.9	0.7	0.9
Capitalized Stock-Based Compensation Expense	0.0	0.0	0.0
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	0.0	0.0	0.1
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	1.4	1.1	1.5
Unrecognized Compensation Cost	$ 1.3
Weighted Average Period for Recognition	1 year 8 months 12 days
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 0.7	$ 0.5	$ 0.6
Unrecognized Compensation Cost	$ 0.6
Weighted Average Period for Recognition	1 year 8 months 12 days

- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References + Details

Employee Stock and Incentive Plans - Non-Qualified Stock Options (Details) - USD ($)
$ / shares in Units, $ in Millions

12 Months Ended

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2008

Number of Options [Abstract]

Outstanding as of January 1,

460,234

560,887

646,235

Granted

^[1]

Exercised

49,075

80,798

40,769

Forfeited

15,481

19,855

44,579

Outstanding as of December 31,

395,678

460,234

560,887

Exercisable as of December 31,

395,678

460,234

523,491

Weighted Average Exercise Price [Abstract]

Outstanding as of January 1,

$ 41.68

$ 40.69

$ 40.05

Granted

^[1]

Exercised

35.84

34.25

27.76

Forfeited

44.86

43.96

43.16

Outstanding as of December 31,

42.28

41.68

40.69

Exercisable as of December 31,

$ 41.71

$ 41.59

$ 39.76

Proceeds from Stock Options Exercised

$ 0.1

Weighted Average Grant Date Intrinsic Value of Options Granted

$ 6.18

Total Intrinsic Value of Options Exercised

$ 0.3

$ 0.5

$ 0.3

[1]	Stock options have not been granted since 2008. The weighted-average grant-date intrinsic value of options granted in 2008 was $6.18.

Employee Stock and Incentive Plans - Stock Options, Range of Exercise Price (Details)	12 Months Ended
	Dec. 31, 2012 $ / shares shares
$23.79 to $26.91 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 23.79
Exercise Price Range, Upper Range Limit	$ 26.91
Number Outstanding \| shares	1,340
Weighted Average Remaining Contractual Term (in Years)	1 month 6 days
Weighted Average Exercise Price	$ 23.79
Number Exercisable \| shares	1,340
Weighted Average Remaining Contractual Term (in Years)	1 month 6 days
Weighted Average Exercise Price	$ 23.79
$37.76 to $41.35 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	37.76
Exercise Price Range, Upper Range Limit	$ 41.35
Number Outstanding \| shares	236,052
Weighted Average Remaining Contractual Term (in Years)	3 years 6 months
Weighted Average Exercise Price	$ 39.64
Number Exercisable \| shares	236,052
Weighted Average Remaining Contractual Term (in Years)	3 years 6 months
Weighted Average Exercise Price	$ 39.64
$44.15 to $48.65 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	44.15
Exercise Price Range, Upper Range Limit	$ 48.65
Number Outstanding \| shares	158,286
Weighted Average Remaining Contractual Term (in Years)	3 years 7 months 6 days
Weighted Average Exercise Price	$ 46.38
Number Exercisable \| shares	158,286
Weighted Average Remaining Contractual Term (in Years)	3 years 7 months 6 days
Weighted Average Exercise Price	$ 46.38

Employee Stock and Incentive Plans - Performance Shares and Restricted Stock Units (Details) - USD ($)
$ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Mar. 31, 2013

Mar. 31, 2012

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Performance Shares [Member]

Number of Shares [Abstract]

As of January 1,

107,899

128,333

122,489

121,825

Granted

41,332

33,525

38,764

^[1]

39,312

^[1]

49,302

^[1]

Awarded

18,605

(41,009)

(32,368)

Unearned Grant Award

(17,575)

(22,909)

Forfeited

(614)

(1,100)

(25,729)

As of December 31,

107,899

128,333

122,489

Weighted Average Grant Date Fair Value [Abstract]

As of January 1,

$ 40.73

$ 36.54

$ 38.15

$ 41.96

Granted

^[1]

44.70

41.00

35.44

Awarded

34.25

48.10

0.00

Unearned Grant Award

34.25

0.00

54.50

Forfeited

34.49

34.35

36.45

As of December 31,

$ 40.73

$ 36.54

$ 38.15

Performance Period

3 years

Grants, Grant Date Fair Value

$ 2.2

$ 1.5

Awards, Grant Date Fair Value

$ 0.7

$ 1.4

Restricted Stock Units [Member]

Number of Shares [Abstract]

As of January 1,

56,415

63,464

43,803

28,983

Granted

19,193

16,355

18,162

^[2]

20,136

^[2]

26,589

^[2]

Awarded

20,939

(24,707)

(215)

(3,091)

Forfeited

(504)

(260)

(8,678)

As of December 31,

56,415

63,464

43,803

Weighted Average Grant Date Fair Value [Abstract]

As of January 1,

$ 36.61

$ 32.57

$ 30.61

$ 29.41

Granted

^[2]

40.83

36.74

31.83

Awarded

29.43

30.30

29.75

Forfeited

31.80

29.41

30.62

As of December 31,

$ 36.61

$ 32.57

$ 30.61

Performance Period

3 years

Grants, Grant Date Fair Value

$ 0.8

$ 0.7

Awards, Grant Date Fair Value

$ 0.7

[1]	Shares granted includes accrued dividends.
[2]	Shares granted includes accrued dividends.

Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Data (Unaudited) [Abstract]
Operating Revenue	$ 256.0	$ 248.8	$ 216.4	$ 240.0	$ 239.2	$ 226.9	$ 219.9	$ 242.2	$ 961.2	$ 928.2	$ 907.0
Operating Income	47.9	45.6	23.3	38.4	34.2	38.9	26.1	50.8	155.2	150.0	135.8
Net Income Attributable to ALLETE	$ 28.9	$ 29.4	$ 14.4	$ 24.4	$ 19.1	$ 20.5	$ 17.0	$ 37.2	$ 97.1	$ 93.8	$ 75.3
Basic Earnings Per Share of Common Stock	$ 0.76	$ 0.78	$ 0.39	$ 0.66	$ 0.53	$ 0.57	$ 0.49	$ 1.07	$ 2.59	$ 2.66	$ 2.20
Diluted Earnings Per Share of Common Stock	$ 0.75	$ 0.78	$ 0.39	$ 0.66	$ 0.53	$ 0.57	$ 0.48	$ 1.07	$ 2.58	$ 2.65	$ 2.19