Derivative Instruments and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Detail) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Foreign Exchange Contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	$ 1,731	$ 2,766
Cross-Currency Swaps | Net investment hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	2,119	910
Interest Rate Swaps | Fair value hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	700	700
Forward Starting Interest Rate Swaps | Cash flow hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	500	500
Foreign Currency-Denominated Debt | Net investment hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	$ 1,524	$ 2,140