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	$ 92,701	87,529				70,774		16,755
Cash dividends paid to parent by MGE		0
Distributions to parent from noncontrolling interest		(10,500)						(10,500)
Ending balance, shares at Sep. 30, 2021			36,163	17,348
Ending balance, value at Sep. 30, 2021		948,641		$ 17,348	252,917	530,925	0	147,451
Beginning balance, shares at Jun. 30, 2021			36,163	17,348
Beginning balance, value at Jun. 30, 2021		918,640		$ 17,348	252,917	503,551	0	144,824
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	34,917	33,001				27,374		5,627
Distributions to parent from noncontrolling interest		(3,000)						(3,000)
Ending balance, shares at Sep. 30, 2021			36,163	17,348
Ending balance, value at Sep. 30, 2021		948,641		$ 17,348	252,917	530,925	0	147,451
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	89,901	84,481				68,534		15,947
Cash dividends paid to parent by MGE		(21,000)				(21,000)
Distributions to parent from noncontrolling interest		(17,500)						(17,500)
Ending balance, shares at Sep. 30, 2022			36,163	17,348
Ending balance, value at Sep. 30, 2022		998,375		$ 17,348	252,917	581,076	0	147,034
Beginning balance, shares at Jun. 30, 2022			36,163	17,348
Beginning balance, value at Jun. 30, 2022		978,824		$ 17,348	252,917	562,878	0	145,681
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 33,720	32,801				27,198		5,603
Cash dividends paid to parent by MGE		(9,000)				(9,000)
Distributions to parent from noncontrolling interest		(4,250)						(4,250)
Ending balance, shares at Sep. 30, 2022			36,163	17,348
Ending balance, value at Sep. 30, 2022		$ 998,375		$ 17,348	$ 252,917	$ 581,076	$ 0	$ 147,034