Schedule I - Condensed Parent Company Finanical Statements (Details-Cash Flow Statement) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Cash Flow Statements, Captions [Line Items]
Cash provided by operating activities	$ 153,735	$ 137,527	$ 172,443
Investing Activities:
Other	70	221	(1,672)
Cash used for investing activities	(180,145)	(156,975)	(210,412)
Financing Activities:
Proceeds from Issuance of Common Stock	0	0	79,635
Cash dividends paid on common stock	(57,500)	(54,788)	(51,729)
Other	(2,068)	(2,197)	(1,553)
Cash Provided by (Used for) Financing Activities	25,543	(8,756)	59,194
Change in cash, cash equivalents, and restricted cash:	(867)	(28,204)	21,225
Cash, cash equivalents, and restricted cash at beginning of period	18,835	47,039	25,814
Cash, cash equivalents, and restricted cash at end of period	17,968	18,835	47,039
MGE Energy [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash provided by operating activities	58,253	27,535	27,631
Investing Activities:
Contributions to affiliates	(2,693)	0	(32,157)
Contributions to other Investments	(2,357)	(4,006)	(3,809)
Other	861	843	622
Cash used for investing activities	(4,189)	(3,163)	(35,344)
Financing Activities:
Proceeds from Issuance of Common Stock	0	0	79,635
Cash dividends paid on common stock	(57,500)	(54,788)	(51,729)
Other	(187)	(0)	0
Cash Provided by (Used for) Financing Activities	(57,687)	(54,788)	(27,906)
Change in cash, cash equivalents, and restricted cash:	(3,623)	(30,416)	(20,193)
Cash, cash equivalents, and restricted cash at beginning of period	6,959	37,375	17,182
Cash, cash equivalents, and restricted cash at end of period	$ 3,336	$ 6,959	$ 37,375