Fair Value of Financial Instruments (Details-4) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance		$ (866)	$ 178	$ (14,055)
Realized and unrealized gains (losses):
Included in regulatory assets		(1,738)	(1,044)	0
Included in regulatory liability		0	0	14,234
Included in other comprehensive income		0	0	0
Included in earnings	[1]	(9,211)	14,140	5,521
Included in current assets		0	118	237
Purchases		0	11,997	26,287
Sales		0	0	0
Issuances		0	0	0
Settlements		9,211	(26,255)	(32,046)
Ending balance		$ (2,604)	$ (866)	$ 178

[1] MGE's exchange-traded derivative contracts, over-the-counter party transactions, purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset in the financial statements with a corresponding regulatory asset or liability.