Derivative and Hedging Instruments (Details-1) $ in Thousands		12 Months Ended
		Dec. 31, 2022 USD ($) Dth1 MWh MW	Dec. 31, 2021 USD ($) Dth1 MWh MW	Dec. 31, 2020 USD ($)
Derivative Fair Values [Abstract]
Collateral posted against derivative positions			$ 1,300
Other Current Assets [Member]
Derivative Fair Values [Abstract]
Derivative fair value, net		$ 2,747	770	$ 1,162
Commodity Contracts And Financial Transimission Rights [Member]
Derivative Fair Values [Abstract]
Derivative fair value, net		$ (5,100)	$ 2,800
Commodity Contract [Member]
Notional Disclosures [Abstract]
Notional amount, energy measure (in MWh) | MWh		353,600	278,000
Notional amount, decatherm measure (in Dth) | Dth1		8,070,000	5,735,000
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis		$ 2,966	$ 3,379
Liability Derivatives, fair value, gross basis		8,163	849
Collateral posted against derivative positions		0	1,254
Commodity Contract [Member] | Other Current Assets [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	[1]		2,959
Liability Derivatives, fair value, gross basis	[1]		811
Commodity Contract [Member] | Other Deferred Charges [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	[1]		420
Liability Derivatives, fair value, gross basis	[1]		38
Commodity Contract [Member] | Other Current Liabilities [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	[2]	2,164
Liability Derivatives, fair value, gross basis	[2]	7,687
Commodity Contract [Member] | Other Deferred Liabilities and Other [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis	[2]	802
Liability Derivatives, fair value, gross basis	[2]	476
Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative Fair Values [Abstract]
Derivative, right to reclaim collateral (receivable)		$ 5,200
Collateral posted against derivative positions			$ 1,300
Financial Transmission Rights [Member]
Notional Disclosures [Abstract]
Notional amount, power measure (in MW) | MW		1,945	2,127
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis		$ 103	$ 227
Collateral posted against derivative positions		0	0
Financial Transmission Rights [Member] | Other Current Assets [Member]
Derivative Fair Values [Abstract]
Asset Derivatives, fair value, gross basis		103	227
Liability Derivatives, fair value, gross basis		$ 0	$ 0
Energy Related Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Maximum term of derivative hedging contract		4 years
PPA [Member]
Notional Disclosures [Abstract]
Notional amount, power measure (in MW) | MW		0	250
Derivative Fair Values [Abstract]
Liability Derivatives, fair value, gross basis			$ 2,140
PPA [Member] | Other Current Liabilities [Member]
Derivative Fair Values [Abstract]
Liability Derivatives, fair value, gross basis			$ 2,140

[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] As of December 31, 2022, collateral of $5.2 million was posted against and netted with derivative liability positions on the consolidated balance sheets. The fair value of the derivative liability disclosed in this table has not been reduced for the collateral posted.