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]	Retained Earnings [Member] MGE [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Other Comprehensive Income/(Loss) [Member] MGE [Member]	Noncontrolling Interest [Member] MGE [Member]
Beginning balance, shares at Dec. 31, 2014			34,668	17,348
Beginning balance, value at Dec. 31, 2014		$ 612,260		$ 17,348	$ 192,417		$ 276,662		$ 144	$ 125,689
Cumulative effect of new accounting principle at Dec. 31, 2014	$ (142)	(142)				$ (142)	(142)
Beginning balance, value - Adjusted at Dec. 31, 2014		612,118					276,520
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Net Income		18,311					11,758			6,553
Other comprehensive loss	(85)	(82)						$ (85)	(82)
Equity contribution received by noncontrolling interest		2,678								2,678
Distributions to parent from noncontrolling interest		(6,818)								(6,818)
Ending balance, shares at Mar. 31, 2015			34,668	17,348
Ending balance, value at Mar. 31, 2015		626,207		$ 17,348	192,417		288,278		62	128,102
Beginning balance, shares at Dec. 31, 2015			34,668	17,348
Beginning balance, value at Dec. 31, 2015		641,984		$ 17,348	192,417		291,888		23	140,308
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Net Income		17,197					10,945			6,252
Other comprehensive loss	$ (164)	(30)						$ (164)	(30)
Cash dividends paid to parent by MGE		(10,000)					(10,000)
Equity contribution received by noncontrolling interest		533								533
Distributions to parent from noncontrolling interest		(6,500)								(6,500)
Ending balance, shares at Mar. 31, 2016			34,668	17,348
Ending balance, value at Mar. 31, 2016		$ 643,184		$ 17,348	$ 192,417		$ 292,833		$ (7)	$ 140,593