Fair Value of Financial Instruments (Details-4) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance,		$ 197	$ (1,432)	$ (447)	$ (2,604)
Realized and unrealized gains (losses):
Included in regulatory assets		0	300	0	1,472
Included in regulatory liability		515	0	1,158	0
Included in earnings	[1]	(456)	(1,572)	(1,722)	(5,174)
Settlements		456	1,572	1,723	5,174
Ending balance,		$ 712	$ (1,132)	$ 712	$ (1,132)

[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.