Madison Gas and Electric Company Consolidated Statements of Equity - USD ($) $ 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 (Loss)/ Income [Member] MGE [Member]	Noncontrolling Interest [Member] MGE [Member]
Beginning balance, shares at Dec. 31, 2018			34,668,000	17,348,000
Beginning balance, value at Dec. 31, 2018		$ 689,810		$ 17,348	$ 192,417	$ 338,591	$ 0	$ 141,454
Increase (Decrease) in Equity [Roll Forward]
Net Income	$ 86,874	80,779				58,430		22,349
Capital contributions from parent		30,500			30,500
Cash dividends paid to parent by MGE		0
Distributions to parent from noncontrolling interest		(23,500)						(23,500)
Ending balance, shares at Dec. 31, 2019			34,668,000	17,348,000
Ending balance, value at Dec. 31, 2019		777,589		$ 17,348	222,917	397,021	0	140,303
Increase (Decrease) in Equity [Roll Forward]
Net Income	92,418	85,523				63,130		22,393
Capital contributions from parent		30,000			30,000
Cash dividends paid to parent by MGE		0
Distributions to parent from noncontrolling interest		(21,500)						(21,500)
Ending balance, shares at Dec. 31, 2020			36,163,000	17,348,000
Ending balance, value at Dec. 31, 2020		871,612		$ 17,348	252,917	460,151	0	141,196
Increase (Decrease) in Equity [Roll Forward]
Net Income	$ 105,761	100,782				78,391		22,391
Capital contributions from parent		0
Cash dividends paid to parent by MGE		(5,000)				(5,000)
Distributions to parent from noncontrolling interest		(15,000)						(15,000)
Ending balance, shares at Dec. 31, 2021			36,163,000	17,348,000
Ending balance, value at Dec. 31, 2021		$ 952,394		$ 17,348	$ 252,917	$ 533,542	$ 0	$ 148,587