Commitments and Contingencies (Details-4) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
MGE [Member]
Other Commitments [Line Items]
Other commitments, due in 2016	$ 612
Other commitments, due in 2017	523
Other commitments, due in 2018	509
Other commitments, due in 2019	511
Other commitments, due in 2020	497
Other commitment, due thereafter	6,086
MGE Energy [Member] | Investments in Non Public Entities, Capital Infusions [Member]
Other Commitments [Line Items]
Other commitment, initial agreed upon commitment total	$ 1,600
MGE Energy [Member] | Venture Debt Fund [Member]
Other Commitments [Line Items]
Other commitment, contract term, expiring in 2016	3 years
Other commitment, initial agreed upon commitment total	$ 1,500
Other commitments, total as of balance sheet date	$ 700