v3.25.2
Contingencies and Legal Proceedings Contingencies (Details)
$ in Millions
 3 Months Ended 9 Months Ended
Dec. 31, 2024
Jun. 30, 2025
USD ($)
reactors
Insurance_layers
Procedures
Sep. 30, 2024
USD ($)
Loss Contingencies      
Nuclear liability insurance   $ 500  
Assessment from licensees for each licensed reactor   $ 166  
Number of licensed reactors in US | reactors   95  
Nuclear accident assessment limitation per year per unit   $ 25  
Maximum assessment per nuclear incident   1,200  
Total amount of protection available   16,300  
Amount of insurance available for loss at any one site   2,100  
Maximum amount of retrospective premiums   122  
Maximum idemnity if a covered accident takes or keeps a nuclear unit offline   490  
Maximum retrospective premiums   50  
Estimated future decommissioning cost   $ 10,924 $ 10,806
Number of procedures for determining estimates for the costs of nuclear decommissioning | Procedures   2  
Estimated liability for cleanup and environmental work   $ 10 15
Amount of insurance available for loss at any one site (top range)   2,800  
Long-term debt of VIEs, net (including current maturities)   $ 1,693 966
The U.S. Congress is required to take action if these layes are exhausted | Insurance_layers   2  
Environmental Remediation      
Loss Contingencies      
Accrual for Environmental Loss Contingencies, Significant Assumptions 215 million 313 million  
Accrual for Environmental Loss Contingencies, Significant Assumptions 215 million 313 million  
Nuclear      
Loss Contingencies      
Estimated future decommissioning cost   $ 3,937 3,814
Non-nuclear      
Loss Contingencies      
Estimated future decommissioning cost   $ 6,987 $ 6,992