Schedule I - Condensed Parent Company Finanical Statements (Details-Cash Flow Statement) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Condensed Cash Flow Statements, Captions [Line Items]
Cash provided by operating activities	$ 263,234	$ 277,784	$ 237,561
Investing Activities:
Other	2,155	230	(954)
Cash used for investing activities	(350,561)	(241,487)	(230,020)
Financing Activities:
Proceeds from Issuance of Common Stock	3,750	31,605	0
Cash dividends paid on common stock	(67,587)	(63,596)	(60,393)
Other	(1,836)	(1,690)	(2,576)
Cash (Used for) Provided by Financing Activities	71,567	(26,827)	(10,483)
Change in cash, cash equivalents, and restricted cash:	(15,760)	9,470	(2,942)
Cash, cash equivalents, and restricted cash at beginning of period	24,496	15,026	17,968
Cash, cash equivalents, and restricted cash at end of period	8,736	24,496	15,026
MGE Energy [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash provided by operating activities	76,396	65,883	67,253
Investing Activities:
Contributions to affiliates	(16,885)	(33,429)	(3,750)
Contributions to other Investments	(1,037)	(1,964)	(3,080)
Other	4,466	329	987
Cash used for investing activities	(13,456)	(35,064)	(5,843)
Financing Activities:
Proceeds from Issuance of Common Stock	3,750	31,712	0
Cash dividends paid on common stock	(67,587)	(63,595)	(60,393)
Other	0	(94)	0
Cash (Used for) Provided by Financing Activities	(63,837)	(31,977)	(60,393)
Change in cash, cash equivalents, and restricted cash:	(897)	(1,158)	1,017
Cash, cash equivalents, and restricted cash at beginning of period	3,195	4,353	3,336
Cash, cash equivalents, and restricted cash at end of period	$ 2,298	$ 3,195	$ 4,353