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, 2012			34,668	17,348
Beginning balance, value at Dec. 31, 2012		$ 550,766		$ 17,348	$ 192,417		$ 223,527		$ 4	$ 117,470
Increase (Decrease) in Common Equity [Roll Forward]
Net Income		76,445					49,007			27,438
Other comprehensive income/(loss)	$ 283	188						$ 283	188
Cash dividends paid to parent by MGE	(52,366)	(25,000)					(25,000)
Equity contribution received by noncontrolling interest		1,420								1,420
Distributions to parent from noncontrolling interest		(27,365)								(27,365)
Ending balance, shares at Dec. 31, 2013			34,668	17,348
Ending 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	(47,859)	(26,500)					(26,500)
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
Cumulative effect of new accounting principle (See Footnote 1) at Dec. 31, 2014	(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	$ (44,708)	(30,000)					(30,000)
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