Madison Gas and Electric Company Consolidated Statements of Common Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	MGE [Member]	Common Stock [Member]	Common Stock [Member] MGE [Member]	Additional Paid-in Capital [Member] MGE [Member]	Retained Earnings [Member] MGE [Member]	Accumulated Other Comprehensive Income/(Loss) [Member] MGE [Member]	Noncontrolling Interest [Member] MGE [Member]
Beginning balance, shares at Dec. 31, 2020			36,163	17,348
Beginning balance, value at Dec. 31, 2020		$ 871,612		$ 17,348	$ 252,917	$ 460,151	$ 0	$ 141,196
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 34,933	33,774				28,273		5,501
Cash dividends paid to parent by MGE		0
Distributions to parent from noncontrolling interest		(5,000)						(5,000)
Ending balance, shares at Mar. 31, 2021			36,163	17,348
Ending balance, value at Mar. 31, 2021		900,386		$ 17,348	252,917	488,424	0	141,697
Beginning balance, shares at Dec. 31, 2021			36,163	17,348
Beginning balance, value at Dec. 31, 2021		952,394		$ 17,348	252,917	533,542	0	148,587
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 34,420	32,053				27,297		4,756
Cash dividends paid to parent by MGE		(5,000)				(5,000)
Distributions to parent from noncontrolling interest		(9,000)						(9,000)
Ending balance, shares at Mar. 31, 2022			36,163	17,348
Ending balance, value at Mar. 31, 2022		$ 970,447		$ 17,348	$ 252,917	$ 555,839	$ 0	$ 144,343