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Commitments and Contingencies - Narrative (Details)
$ in Thousands
 12 Months Ended 24 Months Ended
Dec. 31, 2024
USD ($)
agreement
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Dec. 31, 2026
USD ($)
Jun. 30, 2024
regionalTransmissionOrganization
Other Commitments [Line Items]          
Capacity and energy requirement costs $ 6,000 $ 5,600 $ 13,100    
Coal purchase commitment, number of agreements | agreement 2        
Coal purchase commitment costs $ 44,700 43,700 45,100    
Land easement non-lease payments expense 1,800 1,800 1,400    
Payments to acquire productive assets 358,650 287,134 171,134    
Pre-tax benefit 366,892 $ 363,489 $ 357,535    
Number of regional transmission organizations with show cause proceedings | regionalTransmissionOrganization         4
Solar | Forecast          
Other Commitments [Line Items]          
Payments to acquire productive assets       $ 23,600  
Commitments, termination fee       $ 5,000  
OTP | Federal Energy Regulatory Commission          
Other Commitments [Line Items]          
Pre-tax benefit 2,500        
Estimated liability of refund obligation $ 500        
OTP | OTP Land Easements          
Other Commitments [Line Items]          
Long-term purchase commitment, period 99 years        
Long-term purchase commitment, amount $ 62,000        
OTP | Other Commitments          
Other Commitments [Line Items]          
Long-term purchase commitment, amount $ 10,600