MGE Energy Inc Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Comprehensive Income [Abstract]
Net Income	$ 22,584		$ 16,048
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on available-for-sale securities, net of tax	65	[1]	7	[2]
Comprehensive Income	$ 22,649		$ 16,055

[1] Net of $43 tax

[2] Net of $5 tax