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, 2023			36,163	17,348
Beginning balance, value at Dec. 31, 2023		$ 1,053,256		$ 17,348	$ 252,917	$ 633,460	$ 0	$ 149,531
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 57,608	53,954				42,591		11,363
Cash dividends paid to parent by MGE		(24,000)				(24,000)
Distributions to parent from noncontrolling interest		(10,000)						(10,000)
Ending balance, shares at Jun. 30, 2024			36,176	17,348
Ending balance, value at Jun. 30, 2024		1,073,210		$ 17,348	252,917	652,051	0	150,894
Beginning balance, shares at Mar. 31, 2024			36,176	17,348
Beginning balance, value at Mar. 31, 2024		1,067,456		$ 17,348	252,917	646,063	0	151,128
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	23,794	21,754				15,988		5,766
Cash dividends paid to parent by MGE		(10,000)				(10,000)
Distributions to parent from noncontrolling interest		(6,000)						(6,000)
Ending balance, shares at Jun. 30, 2024			36,176	17,348
Ending balance, value at Jun. 30, 2024		1,073,210		$ 17,348	252,917	652,051	0	150,894
Beginning balance, shares at Dec. 31, 2024			36,490	17,348
Beginning balance, value at Dec. 31, 2024		1,139,805		$ 17,348	283,667	688,404	0	150,386
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	68,090	64,278				52,965		11,313
Cash dividends paid to parent by MGE		(23,500)				(23,500)
Distributions to parent from noncontrolling interest		(8,000)						(8,000)
Ending balance, shares at Jun. 30, 2025			36,542	17,348
Ending balance, value at Jun. 30, 2025		1,172,583		$ 17,348	283,667	717,869	0	153,699
Beginning balance, shares at Mar. 31, 2025			36,537	17,348
Beginning balance, value at Mar. 31, 2025		1,162,108		$ 17,348	283,667	709,108	0	151,985
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 26,498	24,475				18,761		5,714
Cash dividends paid to parent by MGE		(10,000)				(10,000)
Distributions to parent from noncontrolling interest		(4,000)						(4,000)
Ending balance, shares at Jun. 30, 2025			36,542	17,348
Ending balance, value at Jun. 30, 2025		$ 1,172,583		$ 17,348	$ 283,667	$ 717,869	$ 0	$ 153,699