Fair Value of Financial Instruments (Details-5) - 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 [Line Items]
Included in earnings	[1]	$ (6,209)	$ (9,211)	$ 14,140
Purchased Power Expense [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Included in earnings		$ (6,209)	$ (9,211)	$ 14,497
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Utilities Operating Expense, Purchased Power	Utilities Operating Expense, Purchased Power	Utilities Operating Expense, Purchased Power
Cost Of Gas Sold Expense [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Included in earnings		$ 0	$ 0	$ (357)
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Utilities Operating Expense, Cost of Gas Sold	Utilities Operating Expense, Cost of Gas Sold	Utilities Operating Expense, Cost of Gas Sold

[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.