Noncontrolling Interest (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
MGE Power [Member]
Noncontrolling Interest [Line Items]
Ownership percentage by parent		100.00%
MGE [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest on balance sheet		$ 150,386	$ 149,531
Net income attributable to noncontrolling interest, net of tax		$ 22,855	21,868	$ 21,576
MGE Power Elm Road [Member]
Noncontrolling Interest [Line Items]
Ownership percentage by parent		100.00%
Noncontrolling interest on balance sheet	[1]	$ 104,304	103,751
Net income attributable to noncontrolling interest, net of tax	[1]	$ 15,553	14,668	14,326
MGE Power West Campus [Member]
Noncontrolling Interest [Line Items]
Ownership percentage by parent		100.00%
Noncontrolling interest on balance sheet	[1]	$ 46,082	45,780
Net income attributable to noncontrolling interest, net of tax	[1]	$ 7,302	$ 7,200	$ 7,250

[1] MGE Power Elm Road and MGE Power West Campus are not subsidiaries of MGE; however, they have been consolidated in the consolidated financial statements of MGE (see Footnote 3). MGE Power Elm Road and MGE Power West Campus are 100% owned by MGE Power, and MGE Power is 100% owned by MGE Energy. MGE Energy's proportionate share of the equity and net income (through its wholly owned subsidiary MGE Power) of MGE Power Elm Road and MGE Power West Campus is classified within the MGE consolidated financial statements as noncontrolling interest.