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Commitments and Contingencies - Narrative (Details)
$ in Millions
 1 Months Ended 12 Months Ended
Jan. 03, 2023
USD ($)
Jun. 30, 2022
MWh
Dec. 31, 2022
USD ($)
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Other Commitments [Line Items]          
Capacity and energy requirement costs     $ 13.1 $ 11.5 $ 11.3
Coal purchase commitment costs     45.1 40.4 37.9
Land easement non-lease payments expense     1.4 $ 1.3 $ 1.3
OTP          
Other Commitments [Line Items]          
Wind farm, megawatts | MWh   62.4      
OTP | Subsequent Event          
Other Commitments [Line Items]          
Payments to acquire wind farm $ 50.6        
OTP | Federal Energy Regulatory Commission          
Other Commitments [Line Items]          
Estimated liability of refund obligation     2.6    
OTP | Construction Programs          
Other Commitments [Line Items]          
Long-term purchase commitment, amount     21.5    
OTP | OTP Land Easements          
Other Commitments [Line Items]          
Long-term purchase commitment, amount     $ 33.1