Derivative Instruments and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Debt | Net Investment Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 2,140	$ 2,543
Forward exchange contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	2,766	2,735
Currency Swap | Net Investment Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	910	1,958
Fixed To Floating | Fair Value Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	700	700
Interest rate swaps | Cash Flow Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 500	$ 1,000