v3.25.2
Regulatory Assets and Liabilities (Details)
$ in Millions
Jun. 30, 2025
USD ($)
Sep. 30, 2024
USD ($)
Regulatory Assets and Liabilities    
Current regulatory assets $ 152 $ 191
Non-current regulatory assets 9,137 9,408
Environmental Remediation Costs Recognized [Abstract] 313 215
Regulatory assets 9,289 9,599
Current regulatory liabilities 202 174
Regulatory Liability, Noncurrent 85 83
Regulatory Liabilities 287 257
Fair value $ 8 $ 64
Commodity Contract Derivatives    
Regulatory Assets and Liabilities    
Number of contracts 57 45
Derivative, Nonmonetary Notional Amount 412,000,000 321,000,000
Fair value $ 1 $ 2
Fuel cost adjustment tax equivalents    
Regulatory Assets and Liabilities    
Current regulatory liabilities 189 169
Unrealized gains/losses on commodity derivatives    
Regulatory Assets and Liabilities    
Current regulatory liabilities 13 5
Regulatory Liability, Noncurrent 17 2
Postretirement Benefit Costs    
Regulatory Assets and Liabilities    
Regulatory Liability, Noncurrent 68 81
Unrealized losses on interest rate derivatives [Member]    
Regulatory Assets and Liabilities    
Current regulatory assets 51 54
Non-current regulatory assets 321 447
Unrealized gains/losses on commodity derivatives    
Regulatory Assets and Liabilities    
Current regulatory assets 22 102
Non-current regulatory assets 8 64
Fuel cost adjustment receivable/liability    
Regulatory Assets and Liabilities    
Current regulatory assets 79 35
Pension Costs [Member]    
Regulatory Assets and Liabilities    
Non-current regulatory assets 1,915 1,979
Nuclear desommissioning costs [Member]    
Regulatory Assets and Liabilities    
Non-current regulatory assets 276 362
Non-nuclear decommissioning [Member]    
Regulatory Assets and Liabilities    
Non-current regulatory assets 6,135 6,187
Other non-current regulatory assets [Member]    
Regulatory Assets and Liabilities    
Non-current regulatory assets $ 169 $ 154