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Percentage of principal at which debt was extinguished.

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Tax exempt Industrial Development Revenue Bonds.

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No definition available.

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The dividend or interest rate, if any, associated with the financial instrument issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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The rate of interest that was being paid on the original debt issue that is being converted in the noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Interest rate stated in the contractual debt agreement.

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Gross amount of debt extinguished.

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No definition available.

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

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Describes the event or transaction that occurred between the balance sheet date and the date the financial statements are issued or available to be issued.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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Subsequent Events (Details) (USD $)	3 Months Ended		4 Months Ended		3 Months Ended
Subsequent Events (Details) (USD $)	Mar. 31, 2012	Mar. 31, 2011	Apr. 30, 2012 ATC Capital Contribution [Member] Mge Transco [Member]	Apr. 02, 2012 Issuance of Debt [Member]	Apr. 03, 2012 Repayment of Debt [Member]	Apr. 02, 2012 Debt Conversion [Member]
ATC capital contribution [Abstract]
Subsequent Event, Description			On April 30, 2012, MGE Transco made a voluntary $0.5 million capital contribution to ATC.
Contributions to ATC	$ 355,000	$ 425,000	$ 500,000
Debt Instruments [Abstract]
Unsecured debt				28,000,000
Interest rate on secured long-term debt				4.38%	5.875%
Redeemed and retired debt					28,000,000
Extinguishment at percent of principal					100.00%	100.00%
Tax exempt debt						$ 19,300,000
Interest rate before remarketing						4.875%
Interest rate after remarketing						3.45%
Extinguishment at percent of principal					100.00%	100.00%