Schedule I - Condensed Parent Company Finanical Statements (Details-Notes 2) $ in Thousands		12 Months Ended
	Dec. 01, 2016 USD ($)	Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
First Mortgage Bonds [Member] | 7.70%, 2028 Series
Dividend Restrictions
Debt covenant, allowable amount available for payment of dividends		$ 338,500
MGE [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates		50,000	[1]	$ 30,000	$ 26,500
Dividend in kind from affiliate	$ 15,800	$ 15,822		0	0
Dividend Restrictions
Common equity ratio		0.602
Amount available for dividend payments without regulatory approval		$ 43,000
MGE [Member] | Minimum [Member]
Dividend Restrictions
Dividend restrictions, common equity ratio		0.55
MGE [Member] | First Mortgage Bonds [Member] | 7.70%, 2028 Series
Dividend Restrictions
Debt covenant, allowable amount available for payment of dividends		$ 338,500
MGE Power Elm Road [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates		13,500		10,000	13,500
MGE Power West Campus [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates		9,500		3,000	6,000
MGE Transco [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates		1,107		1,708	1,859
MGE Energy [Member]
Dividends from Affiliates [Line Items]
Dividends from affiliates		$ 74,107		$ 44,708	$ 47,859
Dividend in kind from affiliate	$ (15,800)

[1] Excludes $15.8 million dividend in kind to MGE Energy from MGE.