MGE Energy Inc Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Comprehensive Income [Abstract]
Net Income	$ 24,353		$ 23,642		$ 60,828		$ 53,960
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on available-for-sale securities, net of tax	36	[1]	(8)	[2]	176	[3]	35	[1]
Comprehensive Income	$ 24,389		$ 23,634		$ 61,004		$ 53,995

[1] Net of $24 tax

[2] Net of $5 tax

[3] Net of $117 tax