v3.25.0.1
CONTINGENCIES, COMMITMENTS, AND GUARANTEES - MPC and Traditional Electric Operating Companies Other Matters (Details) - USD ($)
$ in Millions
 12 Months Ended 60 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2025
Loss Contingencies [Line Items]        
Period costs $ 130 $ 90    
Mississippi Power        
Loss Contingencies [Line Items]        
Period costs 0 0    
Alabama Power        
Loss Contingencies [Line Items]        
Period costs 8 0    
Kemper County energy facility assets, net | Mississippi Power        
Loss Contingencies [Line Items]        
Pre-tax charge to income 12 17 $ 15  
After tax charge to income $ 9 $ 12 $ 12  
Scenario, Forecast | Kemper County energy facility assets, net | Mississippi Power | Maximum        
Loss Contingencies [Line Items]        
Period costs       $ 15