MGE Energy Inc Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Comprehensive Income [Abstract]
Net Income	$ 14,270		$ 12,723		$ 30,318		$ 30,506
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on available-for-sale securities, net of tax	36	[1]	9	[2]	43	[3]	81	[4]
Reclassification of realized gain on available-for-sale securities, net of tax	0	[5]	(15)	[6]	0	[5]	(15)	[6]
Comprehensive Income	$ 14,306		$ 12,717		$ 30,361		$ 30,572

[1] Net of $24 tax

[2] Net of $6 tax

[3] Net of $29 tax

[4] Net of $54 tax

[5] Net of $0 tax

[6] Net of $10 tax