Financial Instruments - Offsetting of Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020
Foreign currency option contracts
Derivative Assets
Gross Amounts Recognized	$ 0	$ 1
Gross Amounts Offset	0	0
Net Amounts Reported	0	1
Foreign exchange forward contracts
Derivative Assets
Gross Amounts Recognized	2	0
Gross Amounts Offset	0	0
Net Amounts Reported	2	0
Derivative Liabilities
Gross Amounts Recognized	0	1
Gross Amounts Offset	0	0
Net Amounts Reported	$ 0	$ 1

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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