XML 144 R88.htm IDEA: XBRL DOCUMENT v3.25.3
Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Derivative Instruments That Receive Hedge Accounting Treatment (Details) - USD ($)
$ in Millions
 12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Summary of Derivative Instruments That Receive Hedge Accounting Treatment      
Interest rate swaps $ 698 $ 840  
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Net Amount to be Transferred 14    
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax 3 48 $ 42
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax 1 $ 25 $ 99
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net $ 0