Commitments and Contingencies (Details-2) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Operating expense purchase contracts [Abstract]
Purchase obligation, 2015	$ 22,144
Purchase obligation, 2016	50,883
Purchase obligation, 2017	28,647
Purchase obligation, 2018	24,461
Purchase obligation, 2019	20,821
Coal [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2015	6,211	[1]
Purchase obligation, 2016	21,639	[1]
Purchase obligation, 2017	10,664	[1]
Purchase obligation, 2018	6,560	[1]
Purchase obligation, 2019	3,850	[1]
Natural Gas, Transportation and Storage [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2015	5,229	[2]
Purchase obligation, 2016	18,117	[2]
Purchase obligation, 2017	17,983	[2]
Purchase obligation, 2018	17,901	[2]
Purchase obligation, 2019	16,971	[2]
Natual Gas, Supply [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2015	10,704	[3]
Purchase obligation, 2016	11,127	[3]
Purchase obligation, 2017	0	[3]
Purchase obligation, 2018	0	[3]
Purchase obligation, 2019	0	[3]
Columbia Asset Retirement Obligation - Coal Combustion Residual Rule [Member]
Asset Retirement Obligation [Line Items]
Liabilities incurred	$ 2,300

[1] Total coal commitments for the Columbia and Elm Road Units, including transportation. Fuel procurement for MGE's jointly owned Columbia and Elm Road Units is handled by WPL and WEPCO, respectively, who are the operators of those facilities. If any minimum purchase obligations must be paid under these contracts, management believes these obligations would be considered costs of service and recoverable in rates.

[2] MGE's natural gas transportation and storage contracts require fixed monthly payments for firm supply pipeline transportation and storage capacity. The pricing components of the fixed monthly payments for the transportation and storage contracts are established by FERC but may be subject to change.

[3] These commitments include market-bas ed pricing. Management expects to recover these costs in future customer rates.