Derivative and Hedging Instruments (Details-1) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($) Dth1 MWh MW		Dec. 31, 2021 USD ($) Dth1 MWh MW		Jun. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Derivative fair values [Abstract]
Collateral posted against derivative positions	$ 0		$ 1,300
Other Current Assets [Member]
Derivative fair values [Abstract]
Derivative, Fair Value, Net	633		770		$ 161	$ 766	$ 520	$ 1,162
Commodity Contracts And Financial Transimission Rights [Member]
Derivative fair values [Abstract]
Derivative, Fair Value, Net	$ 5,200		$ 2,800
Commodity Contract [Member]
Gross Notional Volume of Open Derivatives [Abstract]
Notional amount, energy measures (in MWh) | MWh	293,200		278,000
Notional amount, decatherm measure (in Dth) | Dth1	8,235,000		5,735,000
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 9,725		$ 3,379
Derivative Liability, Fair Value, Gross Liability	4,614		849
Collateral posted against derivative positions	0		1,254
Commodity Contract [Member] | Other Current Assets [Member]
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset	8,793	[1]	2,959	[2]
Derivative Liability, Fair Value, Gross Liability	4,533	[1]	811	[2]
Commodity Contract [Member] | Other Deferred Charges [Member]
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset	932	[1]	420	[2]
Derivative Liability, Fair Value, Gross Liability	$ 81	[1]	38	[2]
Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative fair values [Abstract]
Collateral posted against derivative positions			$ 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	3,015		2,127
Derivative fair values [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 102		$ 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	102		227
Derivative Liability, Fair Value, Gross Liability	$ 0		$ 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] No collateral was posted against derivative positions as of September 30, 2022.

[2] 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.