Derivative Instruments and Hedging Activities - Schedule of Gross and Net Amounts of Derivative Instruments and Other Amounts (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amount recognized, asset	$ 12	$ 9
Gross amount eligible for offsetting, asset	(8)	(9)
Net amount, asset	4	0
Gross amount recognized, liability	1,148	1,189
Gross amount eligible for offsetting, liability	(8)	(9)
Net amount, liability	$ 1,140	$ 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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Amount of right to receive cash collateral under master netting arrangements offset against derivative liabilities.

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