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Fair Value Measurements Fair Value Measurements Using Significant Unobservable Inputs (Details) - USD ($)
$ in Millions
Mar. 31, 2023
Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Commodity contract derivatives $ 25 $ 152
Commodity contract derivatives 16 7
Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Commodity contract derivatives 0 0
Commodity contract derivatives $ 0 $ 0