Investment in ATC and ATC Holdco (Details-1) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
Apr. 30, 2022	Mar. 31, 2022	Mar. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity earnings from investment		$ 2,504	$ 2,444
Dividends from investment		2,001	1,967
Capital contributions to investments		1,546	670
MGE Transco [Member] \| ATC [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings from investment		2,478	2,420
Dividends from investment		2,001	1,967
Capital contributions to investments		$ 1,243	$ 0
MGE Transco [Member] \| ATC [Member] \| Subsequent Event [Member]
Schedule of Equity Method Investments [Line Items]
Capital contributions to investments	$ 500

Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities.

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