Investment in ATC and ATC Holdco (Details-1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Schedule of Equity Method Investments [Line Items]
Equity earnings from investment			$ 9,586	$ 8,427
Dividends from investments			8,411	6,414
Capital contributions to investments			9,208	4,348
MGE Transco [Member] | ATC [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings from investment	$ 3,224	$ 2,868	9,280	8,338
Dividends from investments	2,403	2,176	8,035	6,414
Capital contributions to investments	$ 3,214	$ 894	$ 8,385	$ 2,679