Madison Gas and Electric Company Consolidated Statements of Common Equity - 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 (Loss)/ Income [Member]	Accumulated Other Comprehensive (Loss)/ Income [Member] MGE [Member]	Noncontrolling Interest [Member] MGE [Member]
Beginning balance, shares at Dec. 31, 2013				34,668	17,348
Beginning balance, value at Dec. 31, 2013		$ 576,454			$ 17,348	$ 192,417		$ 247,534		$ 192	$ 118,963
Increase (Decrease) in Common Equity [Roll Forward]
Net Income		81,938						55,628			26,310
Other comprehensive income (loss)	$ 81	(48)							$ 81	(48)
Cash dividends paid to parent by MGE		(26,500)						(26,500)
Dividend in kind to parent		0
Equity contribution received by noncontrolling interest		1,775									1,775
Distributions to parent from noncontrolling interest		(21,359)									(21,359)
Ending balance, shares at Dec. 31, 2014				34,668	17,348
Ending balance, value at Dec. 31, 2014		612,260			$ 17,348	192,417		276,662		144	125,689
Increase (Decrease) in Common Equity [Roll Forward]
Cumulative effect of new accounting principle	(142)	(142)					$ (142)	(142)
Beginning balance, value - Adjusted at Dec. 31, 2014		612,118						276,520
Increase (Decrease) in Common Equity [Roll Forward]
Net Income		71,465						45,368			26,097
Other comprehensive income (loss)	(101)	(121)							(101)	(121)
Cash dividends paid to parent by MGE		(30,000)						(30,000)
Dividend in kind to parent		0
Equity contribution received by noncontrolling interest		3,230									3,230
Distributions to parent from noncontrolling interest		(14,708)									(14,708)
Ending balance, shares at Dec. 31, 2015				34,668	17,348
Ending balance, value at Dec. 31, 2015		641,984			$ 17,348	192,417		291,888		23	140,308
Increase (Decrease) in Common Equity [Roll Forward]
Net Income		74,592						51,234			23,358
Other comprehensive income (loss)	$ (155)	(4)							$ (155)	(4)
Cash dividends paid to parent by MGE		(50,000)	[1]					(50,000)
Dividend in kind to parent		(15,822)						(15,822)
Equity contribution received by noncontrolling interest		1,598									1,598
Distributions to parent from noncontrolling interest		(24,113)									(24,113)
Deconsolidation of noncontrolling interest		(25,486)									(25,486)
Ending balance, shares at Dec. 31, 2016				34,668	17,348
Ending balance, value at Dec. 31, 2016		$ 602,749			$ 17,348	$ 192,417		$ 277,300		$ 19	$ 115,665

[1] Excludes $15.8 million dividend in kind to MGE Energy from MGE.