Madison Gas and Electric Company Consolidated Statements of Common Equity (Unaudited) (USD $) In Thousands	Total USD ($)	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, 2010		$ 544,309		$ 17,348	$ 192,417	$ 192,480		$ 71	$ 141,993
Beginning balance, shares at Dec. 31, 2010			23,114	17,348
Net Income		30,678				18,753			11,925
Other comprehensive income (loss)	66	17					66	17
Cash dividends paid to parent by MGE		(13,192)				(13,192)
Equity contribution received by noncontrolling interest		622							622
Distributions to parent from noncontrolling interest		(37,000)							(37,000)
Ending balance, value at Jun. 30, 2011		525,434		17,348	192,417	198,041		88	117,540
Ending balance, shares at Jun. 30, 2011			23,114	17,348
Beginning balance, value at Mar. 31, 2011
Net Income		12,811
Ending balance, value at Jun. 30, 2011		525,434		17,348	192,417
Ending balance, shares at Jun. 30, 2011			23,114	17,348
Beginning balance, value at Dec. 31, 2011		527,277		17,348	192,417	203,114		47	114,351
Beginning balance, shares at Dec. 31, 2011			23,114	17,348
Net Income		30,504				18,352			12,152
Other comprehensive income (loss)	43	(23)					43	(23)
Cash dividends paid to parent by MGE		(13,456)				(13,456)
Equity contribution received by noncontrolling interest		888							888
Distributions to parent from noncontrolling interest		(8,500)							(8,500)
Ending balance, value at Jun. 30, 2012		536,690		17,348	192,417	208,010		24	118,891
Ending balance, shares at Jun. 30, 2012			23,114	17,348
Beginning balance, value at Mar. 31, 2012
Net Income		14,290
Ending balance, value at Jun. 30, 2012		$ 536,690		$ 17,348	$ 192,417
Ending balance, shares at Jun. 30, 2012			23,114	17,348