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Investment in ATC and ATC Holdco (Details-1) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2022	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Schedule of Equity Method Investments [Line Items]
Equity earnings from investment				$ 5,127	$ 4,908
Dividends from investment				3,959	3,900
Capital contributions to investments				3,330	2,340
MGE Transco [Member] \| ATC [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings from investment		$ 2,592	$ 2,413	5,070	4,833
Dividends from investment		1,958	1,933	3,959	3,900
Capital contributions to investments		$ 540	$ 0	$ 1,783	$ 0
MGE Transco [Member] \| ATC [Member] \| Subsequent Event [Member]
Schedule of Equity Method Investments [Line Items]
Capital contributions to investments	$ 500