Derivative Instruments and Hedging Activities - Schedule of Fair Values of Derivative Instruments and Other Amounts (Details) - USD ($) $ in Millions	Mar. 31, 2024	Sep. 30, 2023
Derivatives, Fair Value [Line Items]
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]	Other current assets	Other current assets
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other noncurrent assets	Other noncurrent assets
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities	Other current liabilities
Foreign currency exchange derivatives
Derivatives, Fair Value [Line Items]
Total assets		$ 34
Derivatives and Hedging Activities Designated as Hedging Instruments under ASC 815
Derivatives, Fair Value [Line Items]
Total assets	$ 33	30
Derivative liability, noncurrent	0	130
Total liabilities	6	144
Derivatives and Hedging Activities Designated as Hedging Instruments under ASC 815 | Foreign currency exchange derivatives
Derivatives, Fair Value [Line Items]
Derivative asset, current	32	30
Derivative asset, noncurrent	1	0
Derivative liability, current	5	8
Derivative liability, noncurrent	1	6
Derivatives and Hedging Activities Not Designated as Hedging Instruments under ASC 815
Derivatives, Fair Value [Line Items]
Total assets	0	4
Derivative liability, noncurrent	0	0
Total liabilities	1	0
Derivatives and Hedging Activities Not Designated as Hedging Instruments under ASC 815 | Foreign currency exchange derivatives
Derivatives, Fair Value [Line Items]
Derivative asset, current	0	4
Derivative asset, noncurrent	0	0
Derivative liability, current	1	0
Derivative liability, noncurrent	$ 0	$ 0