Madison Gas and Electric Company Consolidated Statements of Common Equity (USD $) In Thousands, unless otherwise specified		Total USD ($)		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 ($)	Comprehensive Income [Member] USD ($)		Comprehensive Income [Member] MGE [Member] USD ($)
Beginning balance, value at Dec. 31, 2008				$ 548,410			$ 17,348	$ 192,417	$ 164,354			$ 134		$ 174,157
Beginning balance, shares at Dec. 31, 2008						22,905	17,348
Net Income				49,752					35,869					13,883			49,752
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax		14	[1]	(22)	[2]					14	[1]	(22)	[2]		14	[1]	(22)	[2]
Total comprehensive income															51,011		49,730
Cash dividends paid to parent by MGE				(19,318)					(19,318)
Equity contribution received by noncontrolling interest				3,551										3,551
Distributions to parent from noncontrolling interest				(12,648)										(12,648)
Ending balance, value at Dec. 31, 2009				569,725			17,348	192,417	180,905			112		178,943
Ending balance, shares at Dec. 31, 2009						23,114	17,348
Net Income				58,465					37,725					20,740			58,465
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax		(63)	[3]	(41)	[4]					(63)	[3]	(41)	[4]		(63)	[3]	(41)	[4]
Total comprehensive income															57,655		58,424
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			61,252
Other comprehensive income/(loss):
Unrealized gain (loss) on available-for-sale securities, net of tax		(15)	[1]	(9)	[5]					(15)	[1]	(9)	[5]		(15)	[1]	(9)	[5]
Reclassification of realized gain on available-for-sale securities, net of tax	[1]	(15)		(15)						(15)		(15)			(15)		(15)
Total comprehensive income															60,898		61,228
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

[1] net of $10 tax

[2] net of $15 tax

[3] net of $42 tax

[4] net of $27 tax

[5] net of $7 tax