Madison Gas and Electric Company Consolidated Statements of Common Equity (Unaudited) (MGE [Member], USD $) In Thousands	MGE [Member] USD ($)	MGE [Member] Common Stock [Member] USD ($)	MGE [Member] Additional Paid-In Capital [Member] USD ($)	MGE [Member] Retained Earnings [Member] USD ($)	MGE [Member] Accumulated Other Comprehensive (Loss)/ Income [Member] USD ($)		MGE [Member] Noncontrolling Interest [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		17,348
Net Income	46,049			30,945			15,104
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	(48)				(48)	[1]
Reclassification of realized gain on available-for-sale securities, net of tax	0
Cash dividends paid to parent by MGE	(19,553)			(19,553)
Equity contribution received by noncontrolling interest	533						533
Distributions to parent from noncontrolling interest	(50,293)						(50,293)
Ending balance, value at Sep. 30, 2010	546,413	17,348	192,417	192,297	64		144,287
Ending balance, shares at Sep. 30, 2010		17,348
Beginning balance, value at Jun. 30, 2010
Net Income	20,101
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	4
Reclassification of realized gain on available-for-sale securities, net of tax	0
Ending balance, value at Sep. 30, 2010	546,413	17,348	192,417
Ending balance, shares at Sep. 30, 2010		17,348
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		17,348
Net Income	51,770			33,835			17,935
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	(20)				(20)	[2]
Reclassification of realized gain on available-for-sale securities, net of tax	(15)				(15)	[3]
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		17,348
Beginning balance, value at Jun. 30, 2011
Net Income	21,092
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	(52)
Reclassification of realized gain on available-for-sale securities, net of tax	0
Ending balance, value at Sep. 30, 2011	$ 534,011	$ 17,348	$ 192,417
Ending balance, shares at Sep. 30, 2011		17,348

[1] net of $32 tax

[2] net of $14 tax

[3] net of $10 tax