Schedule I - Condensed Parent Company Finanical Statements (Details-Notes 2) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
MGE Energy [Member]
Dividends from Affiliates [Line Items]
Cash dividends paid to parent by MGE	$ 25,464	$ 27,714	$ 28,246
First Mortgage Bonds [Member] | 7.70%, 2028 Series [Member]
Dividend Restrictions
Debt covenant, allowable amount available for payment of dividends	604,300
MGE [Member]
Dividends from Affiliates [Line Items]
Cash dividends paid to parent by MGE	$ 5,000	0	0
Dividend Restrictions
Common equity ratio	0.607
MGE [Member] | Minimum [Member]
Dividend Restrictions
Dividend restrictions, common equity ratio	0.55
MGE Power Elm Road [Member]
Dividends from Affiliates [Line Items]
Cash dividends paid to parent by MGE	$ 10,500	15,500	15,500
MGE Power West Campus [Member]
Dividends from Affiliates [Line Items]
Cash dividends paid to parent by MGE	4,500	6,000	8,000
MGE Transco [Member]
Dividends from Affiliates [Line Items]
Cash dividends paid to parent by MGE	5,464	5,864	4,653
MGEE Transco [Member]
Dividends from Affiliates [Line Items]
Cash dividends paid to parent by MGE	$ 0	$ 350	$ 93