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Nuclear Decommissioning - Nuclear Decommissioning Asset Retirement Obligation Rollforward (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Accretion expense $ 158 $ 167
Nuclear Decommissioning    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
ARO beginning balance 12,186  
Accretion expense 154  
Net decrease due to changes in, and timing of, estimated future cash flows (76)  
Costs incurred related to decommissioning plants (4)  
ARO ending balance $ 12,260