MGE Energy Inc Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Comprehensive Income [Abstract]
Net Income	$ 16,048		$ 17,783
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on available-for-sale securities, net of tax	7	[1]	72	[2]
Comprehensive Income	$ 16,055		$ 17,855

[1] Net of $5 tax

[2] Net of $48 tax