Fair Value Measurements - Schedule of the Fair Value Hierarchy for Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Sep. 30, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other current assets
Total assets	$ 33	$ 34
Total liabilities	7	14
Foreign currency exchange derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		34
Foreign currency exchange derivatives | Other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	32
Foreign currency exchange derivatives | Other noncurrent assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	1
Foreign currency exchange derivatives | Other current liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	6	8
Foreign currency exchange derivatives | Other noncurrent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	1	6
Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	0
Quoted Prices in Active Markets (Level 1) | Foreign currency exchange derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		0
Quoted Prices in Active Markets (Level 1) | Foreign currency exchange derivatives | Other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0
Quoted Prices in Active Markets (Level 1) | Foreign currency exchange derivatives | Other noncurrent assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0
Quoted Prices in Active Markets (Level 1) | Foreign currency exchange derivatives | Other current liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	0	0
Quoted Prices in Active Markets (Level 1) | Foreign currency exchange derivatives | Other noncurrent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	33	34
Total liabilities	7	14
Significant Other Observable Inputs (Level 2) | Foreign currency exchange derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		34
Significant Other Observable Inputs (Level 2) | Foreign currency exchange derivatives | Other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	32
Significant Other Observable Inputs (Level 2) | Foreign currency exchange derivatives | Other noncurrent assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	1
Significant Other Observable Inputs (Level 2) | Foreign currency exchange derivatives | Other current liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	6	8
Significant Other Observable Inputs (Level 2) | Foreign currency exchange derivatives | Other noncurrent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	1	6
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	0
Significant Unobservable Inputs (Level 3) | Foreign currency exchange derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		0
Significant Unobservable Inputs (Level 3) | Foreign currency exchange derivatives | Other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0
Significant Unobservable Inputs (Level 3) | Foreign currency exchange derivatives | Other noncurrent assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0
Significant Unobservable Inputs (Level 3) | Foreign currency exchange derivatives | Other current liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	0	0
Significant Unobservable Inputs (Level 3) | Foreign currency exchange derivatives | Other noncurrent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	$ 0	$ 0