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, 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
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			23,114	17,348
Net Income		60,856				40,309			20,547
Other comprehensive income (loss)	176	77					176	77
Cash dividends paid to parent by MGE		0
Equity contribution received by noncontrolling interest		1,065							1,065
Distributions to parent from noncontrolling interest		(21,148)							(21,148)
Ending balance, value at Sep. 30, 2013		591,616		17,348	192,417	263,836		81	117,934
Ending balance, shares at Sep. 30, 2013			23,114	17,348
Beginning balance, value at Jun. 30, 2013
Net Income		24,331
Ending balance, value at Sep. 30, 2013		$ 591,616		$ 17,348	$ 192,417
Ending balance, shares at Sep. 30, 2013			23,114	17,348