Anticipated additional contributions to acquire additional equity in equity method investments.

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The approved percentage return on common equity dedicated to the utility plant in equity method investment.

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- Definition

The amount of the operating expense reported by an equity method investment of the entity.

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The amount of other expense reported by an equity method investment of the entity.

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This item represents disclosure of the amount of dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporation; these investments are accounted for under the equity method of accounting. This element excludes distributions that constitute a return of investment, which are classified as investing activities.

+ References

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-Name Regulation S-X (SX)
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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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- Definition

The amount of net income (loss) reported by an equity method investment of the entity.

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-Name Accounting Standards Codification
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The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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The cash outflow associated with the acquisition of a controlling interest in another entity or an entity that is related to it but not strictly controlled (for example, an unconsolidated subsidiary, affiliate, joint venture or equity method investment).

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Investment in ATC (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 29, 2011	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2011	Dec. 31, 2010
Equity Investments [Abstract]
Percent ownership of equity investment		8.00%		8.00%
Approved percent return on common equity dedicated to utility plant				12.20%
Anticipated additional investment in current fiscal year	$ 0.6					$ 2.0
ALLETE's Investment in ATC
Equity Investment Balance		96.3		96.3			93.3
Cash Investments				1.4	1.2
Equity in ATC Earnings		4.6	4.4	9.0	8.9
Distributed ATC Earnings				(7.4)
ATC Summarized Financial Data
Revenue		138.2	138.7	277.8	277.1
Operating Expense		63.0	62.9	126.1	125.7
Other Expense		19.6	21.7	41.9	42.2
Net Income		55.6	54.1	109.8	109.2
ALLETE's Equity in Net Income		$ 4.6	$ 4.4	$ 9.0	$ 8.9