Madison Gas and Electric Company Consolidated Statements of Common Equity (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, 2009		$ 569,725		$ 17,348	$ 192,417	$ 180,905		$ 112	$ 178,943
Beginning balance, shares at Dec. 31, 2009			23,114	17,348
Net Income		58,465				37,725			20,740
Other Comprehensive income (loss)	(63)	(41)					(63)	(41)
Cash dividends paid to parent by MGE		(26,150)				(26,150)
Equity contribution received by noncontrolling interest		710							710
Distributions to parent from noncontrolling interest		(58,400)							(58,400)
Ending balance, value at Dec. 31, 2010		544,309		17,348	192,417	192,480		71	141,993
Ending balance, shares at Dec. 31, 2010			23,114	17,348
Net Income		61,252				37,282			23,970
Other Comprehensive income (loss)	(30)	(24)					(30)	(24)
Cash dividends paid to parent by MGE		(26,648)				(26,648)
Equity contribution received by noncontrolling interest		888							888
Distributions to parent from noncontrolling interest		(52,500)							(52,500)
Ending balance, value at Dec. 31, 2011		527,277		17,348	192,417	203,114		47	114,351
Ending balance, shares at Dec. 31, 2011			23,114	17,348
Net Income		65,306				40,817			24,489
Other Comprehensive income (loss)	(18)	(43)					(18)	(43)
Cash dividends paid to parent by MGE		(20,404)				(20,404)
Equity contribution received by noncontrolling interest		2,130							2,130
Distributions to parent from noncontrolling interest		(23,500)							(23,500)
Ending balance, value at Dec. 31, 2012		$ 550,766		$ 17,348	$ 192,417	$ 223,527		$ 4	$ 117,470
Ending balance, shares at Dec. 31, 2012			23,114	17,348