Consolidated Statements of Common Equity (Parentheticals) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements of Common Equity and Comprehensive Income
Net unrealized gain (loss) on investments, taxes	$ (10)	$ (42)	$ 10
Reclassification of realized gain on available-for-sale securities, taxes	10	0	0
Dividends per share of common stock	$ 1.52	$ 1.49	$ 1.46
MGE [Member]
Consolidated Statements of Common Equity and Comprehensive Income
Net unrealized gain (loss) on investments, taxes	(7)	(27)	(15)
Reclassification of realized gain on available-for-sale securities, taxes	$ 10	$ 0	$ 0