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	25,948			15,952			9,996
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	(51)				(51)	[1]
Reclassification of realized gain on available-for-sale securities, net of tax	0
Cash dividends paid to parent by MGE	(12,957)			(12,957)
Equity contribution received by noncontrolling interest	533						533
Distributions to parent from noncontrolling interest	(47,203)						(47,203)
Ending balance, value at Jun. 30, 2010	535,995	17,348	192,417	183,900	61		142,269
Ending balance, shares at Jun. 30, 2010		17,348
Beginning balance, value at Mar. 31, 2010
Net Income	11,725
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	(65)
Reclassification of realized gain on available-for-sale securities, net of tax	0
Ending balance, value at Jun. 30, 2010	535,995	17,348	192,417
Ending balance, shares at Jun. 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	30,678			18,753			11,925
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	32				32	[2]
Reclassification of realized gain on available-for-sale securities, net of tax	(15)				(15)	[3]
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		17,348
Beginning balance, value at Mar. 31, 2011
Net Income	12,811
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	(3)
Reclassification of realized gain on available-for-sale securities, net of tax	(15)
Ending balance, value at Jun. 30, 2011	$ 525,434	$ 17,348	$ 192,417
Ending balance, shares at Jun. 30, 2011		17,348

[1] net of $34 tax

[2] net of $21 tax

[3] net of $10 tax