Schedule I - Condensed Parent Company Finanical Statements (Details-Cash Flow Statement) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Cash Flow Statements, Captions [Line Items]
Cash provided by operating activities	$ 237,561	$ 153,735	$ 137,527
Investing Activities:
Other	(954)	70	221
Cash used for investing activities	(230,020)	(180,145)	(156,975)
Financing Activities:
Cash dividends paid on common stock	(60,393)	(57,500)	(54,788)
Other	(2,576)	(2,068)	(2,197)
Cash (Used for) Provided by Financing Activities	(10,483)	25,543	(8,756)
Change in cash, cash equivalents, and restricted cash:	(2,942)	(867)	(28,204)
Cash, cash equivalents, and restricted cash at beginning of period	17,968	18,835	47,039
Cash, cash equivalents, and restricted cash at end of period	15,026	17,968	18,835
MGE Energy [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash provided by operating activities	67,253	58,253	27,535
Investing Activities:
Contributions to affiliates	(3,750)	(2,693)	0
Contributions to other Investments	(3,080)	(2,357)	(4,006)
Other	987	861	843
Cash used for investing activities	(5,843)	(4,189)	(3,163)
Financing Activities:
Cash dividends paid on common stock	(60,393)	(57,500)	(54,788)
Other	0	(187)	0
Cash (Used for) Provided by Financing Activities	(60,393)	(57,687)	(54,788)
Change in cash, cash equivalents, and restricted cash:	1,017	(3,623)	(30,416)
Cash, cash equivalents, and restricted cash at beginning of period	3,336	6,959	37,375
Cash, cash equivalents, and restricted cash at end of period	$ 4,353	$ 3,336	$ 6,959