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A description of the related party transaction, including transactions to which no amounts or nominal amounts were ascribed and such other information deemed necessary to an understanding of the effects of the transactions on the financial statements. Examples of common related party transactions are, sales, purchases and transfers of realty and personal property, services received or furnished, loans and leases to and from top management and affiliates.

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+ Details

Investment in ATC (Details-1) (USD $)	9 Months Ended			9 Months Ended
Investment in ATC (Details-1) (USD $)	Sep. 30, 2010 ATC [Member]	Sep. 30, 2011 ATC [Member]	Dec. 31, 2010 ATC [Member]	Sep. 30, 2011 ATC [Member] Mge Transco [Member]	Sep. 30, 2010 ATC [Member] Mge Transco [Member]
Equity method investments [Line Items]
Equity earnings from investment in ATC				$ 6,400,000	$ 6,400,000
Dividend income from ATC				5,000,000	5,000,000
Contributions to ATC				900,000	500,000
Investment in ATC		56,500,000	54,200,000
Related party transactions [Line Items]
Related party description of transaction	MGE sold a parcel of land in Middleton, Wisconsin to ATC
Related party amounts of transactions	2,700,000
Gain from related party transactions	$ 2,600,000