v3.26.1
Derivative Instruments Gains (Loss) on Derivatives Recognized in Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Financial Swaps | Income Statement Location: us-gaap:RegulatedOperatingRevenue        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss) on Derivative, Net [1] $ 0 $ 243 $ 871 $ 289
Financial Swaps | Income Statement Location: us-gaap:UtilitiesOperatingExpenseFuelUsed        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss) on Derivative, Net [1] (1,078) (536) (27,590) (12,736)
Financial Swaps | Income Statement Location: us-gaap:UtilitiesOperatingExpensePurchasedPower        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss) on Derivative, Net [1] (991) 50 (3,555) (980)
Forward contracts | Income Statement Location: us-gaap:RegulatedOperatingRevenue        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss) on Derivative, Net [1] 23 25 58 391
Forward contracts | Income Statement Location: us-gaap:UtilitiesOperatingExpenseFuelUsed        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss) on Derivative, Net [1] (2,053) (228) (2,392) (831)
Forward contracts | Income Statement Location: us-gaap:UtilitiesOperatingExpensePurchasedPower        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss) on Derivative, Net [1] $ (23) $ (25) $ (58) $ (470)
[1] Excludes unrealized gains or losses on derivatives, which are recorded on the balance sheet as regulatory assets or regulatory liabilities.