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	$ 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
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	59,759	57,250				46,355		10,895
Cash dividends paid to parent by MGE		(21,000)				(21,000)
Distributions to parent from noncontrolling interest		(10,250)						(10,250)
Ending balance, shares at Jun. 30, 2023			36,163	17,348
Ending balance, value at Jun. 30, 2023		1,028,386		$ 17,348	252,917	609,313	0	148,808
Beginning balance, shares at Mar. 31, 2023			36,163	17,348
Beginning balance, value at Mar. 31, 2023		1,013,529		$ 17,348	252,917	595,581	0	147,683
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 28,681	27,607				22,232		5,375
Cash dividends paid to parent by MGE		(8,500)				(8,500)
Distributions to parent from noncontrolling interest		(4,250)						(4,250)
Ending balance, shares at Jun. 30, 2023			36,163	17,348
Ending balance, value at Jun. 30, 2023		$ 1,028,386		$ 17,348	$ 252,917	$ 609,313	$ 0	$ 148,808