Fair Value of Financial Instruments (Details-4) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance		$ (2,604)	$ (866)	$ 178
Realized and unrealized gains (losses):
Included in regulatory assets		0	(1,738)	(1,044)
Included in regulatory liability		2,159	0	0
Included in earnings	[1]	(6,209)	(9,211)	14,140
Included in current assets		0	0	118
Purchases		0	0	11,997
Settlements		6,207	9,211	(26,255)
Ending balance		$ (447)	$ (2,604)	$ (866)

[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.