Fair Value of Financial Instruments (Details-4) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance,		$ 515	$ (1,726)	$ (447)	$ (2,604)
Realized and unrealized gains (losses):
Included in regulatory assets		0	294	0	1,172
Included in regulatory liability		(318)	0	642	0
Included in earnings	[1]	(665)	(1,330)	(1,262)	(3,855)
Settlements		665	1,330	1,264	3,855
Ending balance,		$ 197	$ (1,432)	$ 197	$ (1,432)

[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.