Commitments and Contingencies (Details-1) $ in Thousands	Dec. 31, 2016 USD ($) MW
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation due in next twelve months	$ 122,846
Purchase obligation due in second year	82,295
Purchase obligation due in third year	60,577
Purchase obligation due in fourth year	47,803
Purchase obligation due in fifth year	41,709
Purchase obligation due thereafter	89,562
Coal [Member]
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation due in next twelve months	21,246	[1]
Purchase obligation due in second year	14,763	[1]
Purchase obligation due in third year	7,281	[1]
Purchase obligation due in fourth year	0	[1]
Purchase obligation due in fifth year	0	[1]
Purchase obligation due thereafter	0	[1]
Natural Gas, Transportation and Storage [Member]
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation due in next twelve months	20,859	[2]
Purchase obligation due in second year	20,645	[2]
Purchase obligation due in third year	19,483	[2]
Purchase obligation due in fourth year	15,226	[2]
Purchase obligation due in fifth year	8,443	[2]
Purchase obligation due thereafter	23,331	[2]
Natural Gas, Supply [Member]
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation due in next twelve months	17,783	[3]
Purchase obligation due in second year	0	[3]
Purchase obligation due in third year	0	[3]
Purchase obligation due in fourth year	0	[3]
Purchase obligation due in fifth year	0	[3]
Purchase obligation due thereafter	0	[3]
Purchase Power [Member]
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation due in next twelve months	48,056	[4]
Purchase obligation due in second year	46,563	[4]
Purchase obligation due in third year	33,670	[4]
Purchase obligation due in fourth year	32,577	[4]
Purchase obligation due in fifth year	33,266	[4]
Purchase obligation due thereafter	$ 66,231	[4]
Purchase Power Agreement, Osceola Windpower II, LLC [Member]
Purchase Power Agreement [Abstract]
Long-term purchase commitment, minimum power required (in MW) | MW	50
Other [Member]
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation due in next twelve months	$ 14,902
Purchase obligation due in second year	324
Purchase obligation due in third year	143
Purchase obligation due in fourth year	0
Purchase obligation due in fifth year	0
Purchase obligation due thereafter	$ 0

[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. Management expects to recover these costs in future customer rates.

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

[4] MGE has several purchase power agreements to help meet future electric supply requirements. Management expects to recover these costs in future customer rates. In October 2008, MGE entered into a purchase power agreement to help meet future electric supply requirements. Under this agreement, MGE has agreed to purchase 50  M W of wind power from Osceola Windpower II, LLC, which is located in Iowa. This facility became operational in October 2008. MGE does not have any capacity payment commitments under this agreement. However, MGE is obligated to purchase its ratable share of the energy produced by the project. MGE's commitment related to its ratable share of energy produced by the project has been estimated and is included in the above numbers. Management expects to recover these costs in future customer rates.