v3.25.2
Risk Management Activities and Derivative Transactions Offsetting of Derivative Assets (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Sep. 30, 2024
Offsetting Assets [Line Items]    
Derivative Asset, Subject to Master Netting Arrangement, after Offset $ 30 $ 7
Amount of letters of credit outstanding for credit facilities 6  
Forward Contract Derivative Asset, at Fair Value 18 11
Derivative Liability, Subject to Master Netting Arrangement, after Offset 794 1,122
Offsetting Derivative Assets [Abstract]    
Derivative Asset, Fair Value, Gross Liability 30 4
Letter of Credit    
Offsetting Assets [Line Items]    
Amount of letters of credit outstanding for credit facilities 517 566
Currency Swap    
Offsetting Assets [Line Items]    
Derivative Liability, Subject to Master Netting Arrangement, after Offset 91 116
Commodity Contract under FHP    
Offsetting Assets [Line Items]    
Derivative Asset, Subject to Master Netting Arrangement, after Offset 24 0
Derivative Liability, Subject to Master Netting Arrangement, after Offset 25 161
Offsetting Derivative Assets [Abstract]    
Derivative Asset, Subject to Master Netting Arrangement, before Offset 54 4
Gross amounts of recognized liabilities 55 165
Interest Rate Swap    
Offsetting Assets [Line Items]    
Derivative Liability, Subject to Master Netting Arrangement, after Offset 673 840
Commodity Contract Derivatives    
Offsetting Assets [Line Items]    
Derivative Asset, Subject to Master Netting Arrangement, after Offset 6 7
Derivative Liability, Subject to Master Netting Arrangement, after Offset 5 5
Fair Value, Inputs, Level 2    
Offsetting Assets [Line Items]    
Forward Contract Derivative Asset, at Fair Value $ 18 $ 11