Derivative and Hedging Instruments (Details-1) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) Dth1 MWh MW		Dec. 31, 2020 USD ($) Dth1 MWh MW		Dec. 31, 2019 USD ($)
Other Current Assets [Member]
Derivative Fair Values [Abstract]
Derivative fair value, net	$ 770		$ 1,162		$ 1,100
Commodity Contracts and Financial Transimission Rights [Member]
Derivative Fair Values [Abstract]
Derivative fair value, net	$ 2,800		$ 200
Commodity Derivative Contracts [Member]
Gross Notional Volume of Open Derivatives
Notional amount, energy measure (in MWh) | MWh	278,000		259,080
Notional amount, decatherm measure (in Dth) | Dth1	5,735,000		6,030,000
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	$ 3,379		$ 806
Liability Derivatives, fair value, gross basis	849		632
Collateral posted against derivative positions	0		0
Commodity Derivative Contracts [Member] | Other Current Assets [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	2,959	[1]	617	[2]
Liability Derivatives, fair value, gross basis	811	[1]	593	[2]
Commodity Derivative Contracts [Member] | Other Deferred Charges [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	420	[1]	189	[2]
Liability Derivatives, fair value, gross basis	38	[1]	39	[2]
Commodity Derivative Contracts [Member] | Cash Flow Hedging [Member]
Derivative Fair Values [Abstract]
Collateral posted against derivative positions	$ 1,300		$ 0
Financial Transmission Rights [Member]
Gross Notional Volume of Open Derivatives
Notional amount, power measure (in MW) | MW	2,127		2,869
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	$ 227
Liability Derivatives, fair value, gross basis			$ 23
Collateral posted against derivative positions			0
Financial Transmission Rights [Member] | Other Current Assets [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	227
Liability Derivatives, fair value, gross basis	$ 0
Financial Transmission Rights [Member] | Other Current Liabilities [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis			0
Liability Derivatives, fair value, gross basis			$ 23
Energy Related Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivatives Fair Value [Line Items]
Maximum term of derivative hedging contract	4 years
PPA [Member]
Gross Notional Volume of Open Derivatives
Notional amount, power measure (in MW) | MW	250		850
Derivative Fair Values [Abstract]
Derivative fair value, net	$ (2,100)		$ (14,100)
Liability Derivatives, fair value, gross basis	2,140		14,140
Collateral posted against derivative positions	0		0
PPA [Member] | Derivative Liability (Current) [Member]
Derivative Fair Values [Abstract]
Liability Derivatives, fair value, gross basis	$ 2,140		10,160
PPA [Member] | Derivative Liability (Long-term) [Member]
Derivative Fair Values [Abstract]
Liability Derivatives, fair value, gross basis			$ 3,980

[1] As of December 31, 2021, MGE received collateral of $1.3 million from counterparties under a master netting agreement for outstanding exchange traded derivative positions. The fair value of the derivative asset disclosed in this table has not been reduced for the collateral received.

[2] No collateral was posted against derivative positions as of December 31, 2020.