Subsequent Events	9 Months Ended
Sep. 30, 2012
Subsequent Events Disclosure [Abstract]
Subsequent Events	14. Subsequent Events - MGE Energy and MGE. ATC Capital Contribution. On October 31, 2012, MGE Transco made a voluntary $0.4 million capital contribution to ATC.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

No definition available.

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