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	$ 57,784	54,528				43,400		11,128
Cash dividends paid to parent by MGE		0
Distributions to parent from noncontrolling interest		(7,500)						(7,500)
Ending balance, shares at Jun. 30, 2021			36,163	17,348
Ending balance, value at Jun. 30, 2021		918,640		$ 17,348	252,917	503,551	0	144,824
Beginning balance, shares at Mar. 31, 2021			36,163	17,348
Beginning balance, value at Mar. 31, 2021		900,386		$ 17,348	252,917	488,424	0	141,697
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	22,851	20,754				15,127		5,627
Distributions to parent from noncontrolling interest		(2,500)						(2,500)
Ending balance, shares at Jun. 30, 2021			36,163	17,348
Ending balance, value at Jun. 30, 2021		918,640		$ 17,348	252,917	503,551	0	144,824
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	56,181	51,680				41,336		10,344
Cash dividends paid to parent by MGE		(12,000)				(12,000)
Distributions to parent from noncontrolling interest		(13,250)						(13,250)
Ending balance, shares at Jun. 30, 2022			36,163	17,348
Ending balance, value at Jun. 30, 2022		978,824		$ 17,348	252,917	562,878	0	145,681
Beginning balance, shares at Mar. 31, 2022			36,163	17,348
Beginning balance, value at Mar. 31, 2022		970,447		$ 17,348	252,917	555,839	0	144,343
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 21,761	19,627				14,039		5,588
Cash dividends paid to parent by MGE		(7,000)				(7,000)
Distributions to parent from noncontrolling interest		(4,250)						(4,250)
Ending balance, shares at Jun. 30, 2022			36,163	17,348
Ending balance, value at Jun. 30, 2022		$ 978,824		$ 17,348	$ 252,917	$ 562,878	$ 0	$ 145,681