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, 2010		$ 544,309		$ 17,348	$ 192,417	$ 192,480		$ 71	$ 141,993
Beginning balance, shares at Dec. 31, 2010			23,114	17,348
Net Income		17,867				11,934			5,933
Other comprehensive income (loss)	72	35					72	35
Cash dividends paid to parent by MGE		(6,596)				(6,596)
Equity contribution received by noncontrolling interest		356							356
Distributions to parent from noncontrolling interest		(33,000)							(33,000)
Ending balance, value at Mar. 31, 2011		522,971		17,348	192,417	197,818		106	115,282
Ending balance, shares at Mar. 31, 2011			23,114	17,348
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		16,214				10,142			6,072
Other comprehensive income (loss)	7	(16)					7	(16)
Cash dividends paid to parent by MGE		(6,728)				(6,728)
Equity contribution received by noncontrolling interest		355							355
Distributions to parent from noncontrolling interest		0
Ending balance, value at Mar. 31, 2012		$ 537,102		$ 17,348	$ 192,417	$ 206,528		$ 31	$ 120,778
Ending balance, shares at Mar. 31, 2012			23,114	17,348