Commitments and Contingencies (Details-1) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) Turbines MW		Sep. 30, 2018 USD ($) Turbines MW
Operating expense purchase contracts [Abstract]
Purchase obligation, 2018	$ 21,739		$ 21,739
Purchase obligation, 2019	35,835		35,835
Purchase obligation, 2020	11,202		11,202
Purchase obligation, 2021	3,105		3,105
Purchase obligation, 2022	2,286		2,286
Purchase obligation, Thereafter	4,961		4,961
Coal [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2018	6,716	[1]	6,716	[1]
Purchase obligation, 2019	21,188	[1]	21,188	[1]
Purchase obligation, 2020	8,434	[1]	8,434	[1]
Purchase obligation, 2021	828	[1]	828	[1]
Purchase obligation, 2022	0	[1]	0	[1]
Purchase obligation, Thereafter	0	[1]	0	[1]
Natual Gas, Supply [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2018	12,245	[2]	12,245	[2]
Purchase obligation, 2019	13,287	[2]	13,287	[2]
Purchase obligation, 2020	0	[2]	0	[2]
Purchase obligation, 2021	0	[2]	0	[2]
Purchase obligation, 2022	0	[2]	0	[2]
Purchase obligation, Thereafter	0	[2]	0	[2]
Saratoga Wind [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2018	1,006	[3]	1,006	[3]
Purchase obligation, 2019	858	[3]	858	[3]
Purchase obligation, 2020	2,266	[3]	2,266	[3]
Purchase obligation, 2021	1,775	[3]	1,775	[3]
Purchase obligation, 2022	1,784	[3]	1,784	[3]
Purchase obligation, Thereafter	$ 4,459	[3]	$ 4,459	[3]
Saratoga Wind
Saratoga Capacity (MW) | MW	66		66
Saratoga Turbines | Turbines	33		33
Projected Saratoga Wind Project Costs	$ 108,000		$ 108,000
Saratoga Wind Project Costs Year to Date	66,500		66,500
Allowance for Funds Used During Construction
AFUDC - equity funds	$ 600		$ 1,300
Saratoga Wind [Member] | Public Service Commission of Wisconsin [Member]
Allowance for Funds Used During Construction
Authorized AFUDC Rate	100.00%		100.00%
Other [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2018	$ 1,772		$ 1,772
Purchase obligation, 2019	502		502
Purchase obligation, 2020	502		502
Purchase obligation, 2021	502		502
Purchase obligation, 2022	502		502
Purchase obligation, Thereafter	502		502
MGE Energy [Member] | Venture Capital Funds [Member]
Other Commitments [Line Items]
Other commitment, initial agreed upon commitment total	$ 2,300		$ 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.

[2] These commitments include market-based pricing.

[3] In December 2017, the PSCW authorized construction of a 66MW wind farm, consisting of 33 turbines, located near Saratoga, Iowa. MGE received specific approval to recover 100% AFUDC on the project. As of September 30, 2018 , MGE has incurred $ 66.5 million of capital expenditures. After tax, MGE has recognized $0.6 million and $1.3 million, respectively, in AFUDC equity related to this project for the three and nine months ended September 30, 2018 . Construction of the pro ject is expected to be completed by early 2019 , with an estimated capital cost of $108 million.