Investments (Details-2) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
Jan. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity earnings of investments		$ 10,631	$ 9,136	$ 9,270
Dividends from investments		8,508	7,090	7,832
Capital contributions to investments		6,995	5,185	4,027
MGE Energy [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings of investments		120,394	112,180	107,883
MGE Transco [Member] \| ATC [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings of investments		10,515	9,025	9,774
Dividends from investments		8,397	7,090	7,832
Capital contributions to investments		$ 3,750	$ 2,678	0
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	$ 700
MGEE Transco [Member] \| ATC Holdco [Member]
Schedule of Equity Method Investments [Line Items]
Capital contributions to investments		$ 0	$ 0	$ 0
Ownership interest in equity-method investee		4.40%	4.40%

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