Related Party Transactions	12 Months Ended
Dec. 31, 2011
Related Party Transactions Disclosure [Abstract]
Related Party Transactions	25. Related Party Transactions - MGE Energy and MGE. ATC During 2011, 2010, and 2009, MGE recorded $25.0 million, $26.4 million, and $22.7 million, respectively for transmission services received from ATC. MGE also provides a variety of operational, maintenance, and project management work for ATC, which is reimbursed by ATC. For the years ended December 31, 2011 and 2009, MGE had a receivable due from ATC of $0.2 million and $0.1 million, respectively. For the year ended December 31, 2010, MGE had no receivable due from ATC. During March 2010, MGE sold a parcel of land in Middleton, Wisconsin to ATC for $2.7 million, resulting in a gain of $2.6 million (pretax). The transaction was approved by the PSCW. For additional discussion on MGE's relationship with ATC, see Footnote 4.

The entire disclosure for related party transactions, including the nature of the relationship(s), a description of the transactions, the amount of the transactions, the effects of any change in the method of establishing the terms of the transaction from the previous period, stated interest rate, expiration date, terms and manner of settlement per the agreement with the related party, and amounts due to or from related parties. If the entity and one or more other entities are under common ownership or management control and this control affects the operating results or financial position, disclosure includes the nature of the control relationship even if there are no transactions between the entities. Disclosure may also include the aggregate amount of current and deferred tax expense for each statement of earnings presented where the entity is a member of a group that files a consolidated tax return, the amount of any tax related balances due to or from affiliates as of the date of each statement of financial position presented, the principal provisions of the method by which the consolidated amount of current and deferred tax expense is allocated to the members of the group and the nature and effect of any changes in that method. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

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