Schedule I - Condensed Parent Company Finanical Statements (Details-Notes 2) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Dividends from Affiliates [Line Items]
Dividends from affiliates	$ 44,708	$ 47,859	$ 52,366
First Mortgage Bonds [Member] | 7.70%, 2028 Series
Dividend Restrictions
Debt covenant, allowable amount available for payment of dividends	353,000
MGE [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates	$ 30,000	26,500	25,000
Dividend Restrictions
Dividend restrictions, minimum common equity ratio	0.55
Common equity ratio	0.597
Amount available for dividend payments without regulatory approval	$ 43,000
MGE [Member] | First Mortgage Bonds [Member] | 7.70%, 2028 Series
Dividend Restrictions
Debt covenant, allowable amount available for payment of dividends	353,000
MGE Power Elm Road [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates	10,000	13,500	17,300
MGE Power West Campus [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates	3,000	6,000	9,250
MGE Transco [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates	$ 1,708	$ 1,859	$ 816