Consolidated Statements of Common Equity (Unaudited) (Parentheticals) (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
MGE Energy [Member]
Consolidated Statements of Common Equity and Comprehensive Income
Unrealized gain (loss) on available-for-sale securities, taxes	$ 6	$ (59)	$ 54	$ (54)
Reclassification of realized gain on available-for-sale securities, taxes	(10)	0	(10)	0
Dividends per share of common stock	$ 0.375	$ 0.368	$ 0.750	$ 0.737
MGE [Member]
Consolidated Statements of Common Equity and Comprehensive Income
Unrealized gain (loss) on available-for-sale securities, taxes	(2)	(43)	21	(34)
Reclassification of realized gain on available-for-sale securities, taxes	$ (10)	$ 0	$ (10)	$ 0