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, 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
Beginning balance, shares at Dec. 31, 2022			36,163	17,348
Beginning balance, value at Dec. 31, 2022		1,002,386		$ 17,348	252,917	583,958	0	148,163
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	97,616	93,202				76,820		16,382
Cash dividends paid to parent by MGE		(30,000)				(30,000)
Distributions to parent from noncontrolling interest		(17,250)						(17,250)
Ending balance, shares at Sep. 30, 2023			36,163	17,348
Ending balance, value at Sep. 30, 2023		1,048,338		$ 17,348	252,917	630,778	0	147,295
Beginning balance, shares at Jun. 30, 2023			36,163	17,348
Beginning balance, value at Jun. 30, 2023		1,028,386		$ 17,348	252,917	609,313	0	148,808
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 37,857	35,952				30,465		5,487
Cash dividends paid to parent by MGE		(9,000)				(9,000)
Distributions to parent from noncontrolling interest		(7,000)						(7,000)
Ending balance, shares at Sep. 30, 2023			36,163	17,348
Ending balance, value at Sep. 30, 2023		$ 1,048,338		$ 17,348	$ 252,917	$ 630,778	$ 0	$ 147,295