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		51,770				33,835			17,935
Other comprehensive income (loss)	(8)	(35)					(8)	(35)
Cash dividends paid to parent by MGE		(19,921)				(19,921)
Equity contribution received by noncontrolling interest		888							888
Distributions to parent from noncontrolling interest		(43,000)							(43,000)
Ending balance, value at Sep. 30, 2011		534,011		17,348	192,417	206,394		36	117,816
Ending balance, shares at Sep. 30, 2011			23,114	17,348
Beginning balance, value at Jun. 30, 2011
Net Income		21,092
Ending balance, value at Sep. 30, 2011		534,011		17,348	192,417
Ending balance, shares at Sep. 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		54,180				35,875			18,305
Other comprehensive income (loss)	35	(30)					35	(30)
Cash dividends paid to parent by MGE		(13,456)				(13,456)
Equity contribution received by noncontrolling interest		1,775							1,775
Distributions to parent from noncontrolling interest		(15,500)							(15,500)
Ending balance, value at Sep. 30, 2012		554,246		17,348	192,417	225,533		17	118,931
Ending balance, shares at Sep. 30, 2012			23,114	17,348
Beginning balance, value at Jun. 30, 2012
Net Income		23,676
Ending balance, value at Sep. 30, 2012		$ 554,246		$ 17,348	$ 192,417
Ending balance, shares at Sep. 30, 2012			23,114	17,348