Derivative Instruments and Hedging Activities - Schedule of Gross and Net Amounts of Derivative Instruments and Other Amounts (Details) - USD ($) $ in Millions	Jun. 30, 2022	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amount recognized, asset	$ 10	$ 9
Gross amount eligible for offsetting, asset	(10)	(9)
Net amount, asset	0	0
Gross amount recognized, liability	880	1,189
Gross amount eligible for offsetting, liability	(10)	(9)
Net amount, liability	$ 870	$ 1,180

Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets.

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Fair value, before 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 elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, after offset of derivative liability, of 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, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or 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 liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Amount of right to receive cash collateral under master netting arrangements offset against derivative liabilities.

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