Schedule I - Condensed Parent Company Finanical Statements (Details-Cash Flow Statement) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Cash Flow Statements, Captions [Line Items]
Cash provided by operating activities	$ 137,527	$ 172,443	$ 130,475
Investing Activities:
Other	221	(1,672)	(508)
Cash Used for Investing Activities	(156,975)	(210,412)	(172,357)
Financing Activities:
Proceeds From Issuance Of Common Stock	0	79,635	0
Cash dividends paid on common stock	(54,788)	(51,729)	(47,842)
Other	(2,197)	(1,553)	(1,838)
Cash Provided by (Used for) Financing Activities	(8,756)	59,194	(17,233)
Change in cash, cash equivalents, and restricted cash:	(28,204)	21,225	(59,115)
Cash, cash equivalents, and restricted cash at beginning of period	47,039	25,814	84,929
Cash, cash equivalents, and restricted cash at end of period	18,835	47,039	25,814
MGE Energy [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash provided by operating activities	27,535	27,631	27,901
Investing Activities:
Contributions to affiliates	0	(32,157)	(33,631)
Contributions to other Investments	(4,006)	(3,809)	(4,496)
Other	843	622	214
Cash Used for Investing Activities	(3,163)	(35,344)	(37,913)
Financing Activities:
Proceeds From Issuance Of Common Stock	0	79,635	0
Cash dividends paid on common stock	(54,788)	(51,729)	(47,842)
Cash Provided by (Used for) Financing Activities	(54,788)	(27,906)	(47,842)
Change in cash, cash equivalents, and restricted cash:	(30,416)	(20,193)	(57,854)
Cash, cash equivalents, and restricted cash at beginning of period	37,375	17,182	75,036
Cash, cash equivalents, and restricted cash at end of period	$ 6,959	$ 37,375	$ 17,182