Madison Gas and Electric Company Consolidated Statements of Common Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total USD ($)	MGE [Member] USD ($)	Common Stock [Member]	Common Stock [Member] MGE [Member] USD ($)	Additional Paid-In Capital [Member] MGE [Member] USD ($)	Retained Earnings [Member] MGE [Member] USD ($)	Accumulated Other Comprehensive (Loss)/Income [Member] USD ($)	Accumulated Other Comprehensive (Loss)/Income [Member] MGE [Member] USD ($)	Noncontrolling Interest [Member] MGE [Member] USD ($)
Beginning balance, value at Dec. 31, 2012		$ 550,766		$ 17,348	$ 192,417	$ 223,527		$ 4	$ 117,470
Beginning balance, shares at Dec. 31, 2012			34,668	17,348
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Net Income		22,560				15,734			6,826
Other comprehensive income (loss)	65	27					65	27
Equity contribution received by noncontrolling interest		178							178
Distributions to parent from noncontrolling interest		(5,500)							(5,500)
Ending balance, value at Mar. 31, 2013		568,031		17,348	192,417	239,261		31	118,974
Ending balance, shares at Mar. 31, 2013			34,668	17,348
Beginning balance, value at Dec. 31, 2013		576,454		17,348	192,417	247,534		192	118,963
Beginning balance, shares at Dec. 31, 2013			34,668	17,348
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Net Income		27,643				21,133			6,510
Other comprehensive income (loss)	7	18					7	18
Cash dividends paid to parent by MGE		(7,000)				(7,000)
Equity contribution received by noncontrolling interest		533							533
Distributions to parent from noncontrolling interest		(6,909)							(6,909)
Ending balance, value at Mar. 31, 2014		$ 590,739		$ 17,348	$ 192,417	$ 261,667		$ 210	$ 119,097
Ending balance, shares at Mar. 31, 2014			34,668	17,348