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		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
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		22,560				15,734			6,826
Other comprehensive income (loss)	65	27					65	27
Cash dividends paid to parent by MGE		0
Equity contribution received by noncontrolling interest		178							178
Distributions to parent from noncontrolling interest		(5,500)							(5,500)
Ending balance, value at Mar. 31, 2013		$ 568,031		$ 17,348	$ 192,417	$ 239,261		$ 31	$ 118,974
Ending balance, shares at Mar. 31, 2013			23,114	17,348