Schedule I - Condensed Parent Company Finanical Statements (Details-Comprehensive Income Statement) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Utilities Operating Expense [Abstract]
Other operations and maintenance	$ 236,880	$ 228,576	$ 215,891
Total Operating Expenses	573,001	530,682	544,046
Operating Income	170,653	146,262	146,385
Equity earnings of investments	13,009	12,275	10,631
Income before income taxes	156,654	131,165	145,502
Income tax provision	(20,765)	(10,596)	(27,803)
Net Income	135,889	120,569	117,699
MGE Energy [Member]
Utilities Operating Expense [Abstract]
Other operations and maintenance	969	818	868
Total Operating Expenses	969	818	868
Operating Income	(969)	(818)	(868)
Equity earnings of investments	136,204	121,310	120,394
Other income/(loss), net	293	(395)	(2,862)
Interest income, net	252	296	105
Income before income taxes	135,780	120,393	116,769
Income tax provision	109	175	930
Net Income	$ 135,889	$ 120,568	$ 117,699