Variable Interest Entities (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
In-service utility plant, net		$ 1,865,352	$ 1,828,171
Construction work in progress		105,748	50,603
Accrued interest and accrued (prepaid) taxes		7,868	10,385
Deferred income taxes		252,190	231,149
Unamortized discount and debt issuance costs		4,000	4,349
MGE Power Elm Road [Member]
Variable Interest Entity [Line Items]
In-service utility plant, net		161,167	163,325
Construction work in progress		3,410	898
Affiliate receivables		0	0
Accrued interest and accrued (prepaid) taxes		51	37
Deferred income taxes		30,770	30,696
Long-term debt	[1]	46,343	48,968
Noncontrolling interest		103,333	101,507
Unamortized discount and debt issuance costs		300	300
MGE Power West Campus [Member]
Variable Interest Entity [Line Items]
In-service utility plant, net		77,280	79,183
Construction work in progress		809	493
Affiliate receivables		1,668	2,211
Accrued interest and accrued (prepaid) taxes		(8)	(75)
Deferred income taxes		14,986	14,726
Long-term debt	[1]	33,354	35,563
Noncontrolling interest		44,830	47,080
Unamortized discount and debt issuance costs		$ 100	$ 100

[1] MGE Power Elm Road's long-term debt includes debt issuance costs of $0.3 million as of December 31, 2022 and 2021. The debt is secured by a collateral assignment of lease payments that MGE makes to MGE Power Elm Road for use of the Elm Road Units pursuant to the related long-term leases. MGE Power West Campus's long-term debt includes debt issuance costs of $0.1 million as of December 31, 2022 and 2021. The debt is secured by a collateral assignment of lease payments that MGE makes to MGE Power West Campus for use of the cogeneration facility pursuant to the long-term lease. See Footnote 14 for further information on the long-term debt securities.