Asset Retirement Obligations (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligation, beginning balance		$ 46,580	$ 31,196
Liabilities incurred	[1]	1,947	8,589
Accretion expense		1,909	1,526
Liabilities settled		(317)	(354)
Revisions in estimated cash flows	[2]	141	5,623
Asset retirement obligation, ending balance		$ 50,260	46,580
Badger Hollow [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Liabilities incurred			4,900
Other completed renewable projects
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Liabilities incurred			$ 3,400

[1] In 2021, MGE recorded an obligation of $4.9 million and $3.4 million, respectively, for the fair value of its legal liability for AROs associated with Badger Hollow I and other completed renewable projects. See Footnote 6 for additional information on Badger Hollow I.

[2] In 2021, MGE revised the AROs associated with certain Columbia assets.