Commitments and Contingencies (Details-2)	9 Months Ended
	Sep. 30, 2019 USD ($)
Operating expense purchase contracts [Abstract]
Purchase obligation, 2019	$ 22,925,000
Purchase obligation, 2020	46,955,000
Purchase obligation, 2021	31,328,000
Purchase obligation, 2022	24,864,000
Purchase obligation, 2023	22,570,000
Purchase obligation, Thereafter	89,013,000
Coal [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2019	7,293,000	[1]
Purchase obligation, 2020	13,120,000	[1]
Purchase obligation, 2021	5,647,000	[1]
Purchase obligation, 2022	2,313,000	[1]
Purchase obligation, 2023	0	[1]
Purchase obligation, Thereafter	0	[1]
Natural Gas, Transportation and Storage [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2019	6,258,000	[2]
Purchase obligation, 2020	21,997,000	[2]
Purchase obligation, 2021	21,728,000	[2]
Purchase obligation, 2022	21,728,000	[2]
Purchase obligation, 2023	21,728,000	[2]
Purchase obligation, Thereafter	55,460,000	[2]
Natual Gas, Supply [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2019	8,773,000	[3]
Purchase obligation, 2020	10,600,000	[3]
Purchase obligation, 2021	0	[3]
Purchase obligation, 2022	0	[3]
Purchase obligation, 2023	0	[3]
Purchase obligation, Thereafter	0	[3]
Solar farms
Operating expense purchase contracts [Abstract]
Purchase obligation, 2019	509,000	[4]
Purchase obligation, 2020	310,000	[4]
Purchase obligation, 2021	3,024,000	[4]
Purchase obligation, 2022	726,000	[4]
Purchase obligation, 2023	743,000	[4]
Purchase obligation, Thereafter	32,474,000	[4]
Other [Member]
Operating expense purchase contracts [Abstract]
Purchase obligation, 2019	92,000
Purchase obligation, 2020	928,000
Purchase obligation, 2021	929,000
Purchase obligation, 2022	97,000
Purchase obligation, 2023	99,000
Purchase obligation, Thereafter	1,079,000
Two Creeks Construction Commitment [Member]
Long Term Purchase Commitment [Line Items]
Minimum future capital commitments	20,500,000
Badger Hollow Construction Commitment [Member]
Long Term Purchase Commitment [Line Items]
Minimum future capital commitments	53,200,000
MGE Energy [Member] | Venture Capital Funds [Member]
Other Commitments [Line Items]
Other commitment, initial agreed upon commitment total	$ 10,000,000

[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] 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-based pricing.

[4] In 2019, MGE entered into commitments related to operations of the Two Creeks and Badger Hollow Solar Farms. See Footnote 14 for further information on the solar farm construction.