Derivative and Hedging Instruments - Schedule of Derivative Instruments at Gross Value (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Derivative [Line Items]
Hedged Liability, Statement of Financial Position [Extensible Enumeration]	Long-term debt	Long-term debt
Senior Notes
Derivative [Line Items]
Hedged liability, fair value hedge	$ 3,900	$ 3,700
Foreign exchange forward contracts | Designated as Hedging Instruments: | Prepaid expenses and other current assets
Derivative [Line Items]
Assets	49	100
Foreign exchange forward contracts | Designated as Hedging Instruments: | Accrued liabilities
Derivative [Line Items]
Liabilities	74	66
Foreign exchange forward contracts | Not Designated as Hedging Instruments: | Prepaid expenses and other current assets
Derivative [Line Items]
Assets	18	15
Foreign exchange forward contracts | Not Designated as Hedging Instruments: | Accrued liabilities
Derivative [Line Items]
Liabilities	17	16
Cross-currency swaps | Designated as Hedging Instruments: | Other assets
Derivative [Line Items]
Assets	36	178
Cross-currency swaps | Designated as Hedging Instruments: | Other liabilities
Derivative [Line Items]
Liabilities	2	0
Interest rate swaps | Designated as Hedging Instruments: | Other liabilities
Derivative [Line Items]
Liabilities	$ 133	$ 314