Fair Value of Financial Instruments (Details-4) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance,		$ (1,432)	$ (2,892)	$ (2,604)	$ (866)
Realized and unrealized gains (losses):
Included in regulatory assets		300	1,768	1,472	(258)
Included in earnings	[1]	(1,572)	(2,016)	(5,174)	(7,590)
Settlements		1,572	2,016	5,174	7,590
Ending balance,		$ (1,132)	$ (1,124)	$ (1,132)	$ (1,124)

[1] MGE's exchange-traded derivative contracts, over-the-counter party transactions, 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.