Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Related party transaction [Line Items]
Related party description of transaction		MGE sold a parcel of land in Middleton, Wisconsin to ATC
ATC [Member]
Related party transaction [Line Items]
Related party expenses	$ 25.0	$ 26.4	$ 22.7
Due from Related Parties	0.2		0.1
Related party description of transaction		MGE sold a parcel of land in Middleton, Wisconsin to ATC
Related party amounts of transactions		2.7
Gain from related party transactions		$ 2.6

For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

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+ Details

- Definition

Amount of transactions with related party during the financial reporting period.

+ References+ Details

- Definition

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.

+ References

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