v3.26.1
Derivative Instruments and Hedging Activities (Details)
MWh in Thousands, $ in Thousands
3 Months Ended
Mar. 31, 2026
USD ($)
MWh
Sep. 30, 2025
USD ($)
Mar. 31, 2025
USD ($)
Sep. 30, 2024
USD ($)
Dec. 31, 2025
USD ($)
Other Comprehensive Income (Loss), Net of Tax $ (434) $ (434) $ (434) $ (434)  
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent (434)   (434)    
Regulatory assets 73,843       $ 82,136
Derivative [Line Items]          
Deferred Gain (Loss) on Discontinuation of Interest Rate Fair Value Hedge (578)   (578)    
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax 144   144    
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent (434)   $ (434)    
Expected Reclass Amount          
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent 1,700        
Derivative [Line Items]          
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent $ 1,700        
FTR [Member] | Not Designated as Hedging Instrument [Member]          
Derivative Asset, Fair Value, Gross Asset         $ 1,584
Purchase of Units Derivative Instruments Financial Transmission Rights | MWh 972        
Sale of Units Derivative Instruments Financial Transmission Rights | MWh 0        
Derivative, Nonmonetary Notional Amount, Purchase (Sales), Net $ 972        
interest rate hedge | Not Designated as Hedging Instrument [Member]          
Derivative Asset, Fair Value, Gross Asset $ 551