Investments (Details-2) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
Jan. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Equity earnings of investments		$ 9,136	$ 9,270	$ 10,221
Dividends from investments		7,090	7,832	8,998
Capital contributions to investments		5,185	4,027	5,601
MGE Energy [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings of investments		112,180	107,883	92,922
MGE Transco [Member] \| ATC [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings of investments		9,025	9,774	10,167
Dividends from investments		7,090	7,832	8,633
Capital contributions to investments		$ 2,678	$ 0	1,249
Ownership interest in equity-method investee		3.60%	3.60%
MGE Transco [Member] \| ATC [Member] \| Subsequent Event [Member]
Schedule of Equity Method Investments [Line Items]
Capital contributions to investments	$ 400
MGEE Transco [Member] \| ATC Holdco [Member]
Schedule of Equity Method Investments [Line Items]
Capital contributions to investments		$ 0	$ 0	$ 300
Ownership interest in equity-method investee		4.40%	4.40%

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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