v3.26.1
Utility Regulatory Assets and Liabilities and Regulatory Matters - Schedule of Regulatory Assets and Liabilities (Details) - Utilities - USD ($)
$ in Millions
Jun. 30, 2026
Sep. 30, 2025
Jun. 30, 2025
Regulatory Assets      
Total regulatory assets $ 367 $ 340 $ 319
Regulatory Liabilities      
Total regulatory liabilities 315 314 323
Postretirement benefits      
Regulatory Liabilities      
Total regulatory liabilities 13 14 12
Deferred fuel and power refunds      
Regulatory Liabilities      
Total regulatory liabilities 5 4 10
State income tax benefits — distribution system repairs      
Regulatory Liabilities      
Total regulatory liabilities 50 49 45
Excess federal deferred income taxes      
Regulatory Liabilities      
Total regulatory liabilities 237 239 243
Other      
Regulatory Liabilities      
Total regulatory liabilities 10 8 13
Income taxes recoverable      
Regulatory Assets      
Total regulatory assets 114 113 111
Underfunded pension plans      
Regulatory Assets      
Total regulatory assets 96 100 102
Environmental costs      
Regulatory Assets      
Total regulatory assets 25 22 27
Deferred fuel and power costs      
Regulatory Assets      
Total regulatory assets 71 39 15
Removal costs, net      
Regulatory Assets      
Total regulatory assets 29 30 29
Other      
Regulatory Assets      
Total regulatory assets $ 32 $ 36 $ 35