Derivative and Hedging Instruments (Details-1) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2022 USD ($) Dth1 MWh MW	Dec. 31, 2021 USD ($) Dth1 MWh MW	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Derivative fair values [Abstract]
Collateral posted against derivative positions		$ 6,500	$ 1,300
Other Current Assets [Member]
Derivative fair values [Abstract]
Derivative, Fair Value, Net		(161)	770	$ 267	$ 520	$ 173	$ 1,162
Commodity Contracts And Financial Transimission Rights [Member]
Derivative fair values [Abstract]
Derivative, Fair Value, Net		$ 8,500	$ 2,800
Commodity Contract [Member]
Gross Notional Volume of Open Derivatives [Abstract]
Notional amount, energy measures (in MWh) | MWh		315,520	278,000
Notional amount, decatherm measure (in Dth) | Dth1		6,090,000	5,735,000
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset		$ 12,066	$ 3,379
Derivative Liability, Fair Value, Gross Liability		3,694	849
Collateral posted against derivative positions		6,512	1,254
Commodity Contract [Member] | Other Current Assets [Member]
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset	[1]	11,240	2,959
Derivative Liability, Fair Value, Gross Liability	[1]	3,512	811
Commodity Contract [Member] | Other Deferred Charges [Member]
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset	[1]	826	420
Derivative Liability, Fair Value, Gross Liability	[1]	182	38
Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative fair values [Abstract]
Collateral posted against derivative positions		$ 6,500	$ 1,300
Energy Related Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Maximum term of derivative hedging contract		4 years
Financial Transmission Rights [Member]
Gross Notional Volume of Open Derivatives [Abstract]
Notional amount, power measure (in MW) | MW		4,204	2,127
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset		$ 112	$ 227
Collateral posted against derivative positions		0	0
Financial Transmission Rights [Member] | Other Current Assets [Member]
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset			227
Derivative Liability, Fair Value, Gross Liability			$ 0
Financial Transmission Rights [Member] | Derivative Liability (Current) [Member]
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset	[1]	112
Derivative Liability, Fair Value, Gross Liability	[1]	$ 0
PPA [Member]
Gross Notional Volume of Open Derivatives [Abstract]
Notional amount, power measure (in MW) | MW		0	250
Derivative fair values [Abstract]
Derivative Liability, Fair Value, Gross Liability			$ 2,140
PPA [Member] | Derivative Liability (Current) [Member]
Derivative fair values [Abstract]
Derivative Liability, Fair Value, Gross Liability			$ 2,140

[1] As of June 30, 2022 and December 31, 2021, MGE received collateral of $6.5 million and $1.3 million, respectively, 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.