Derivative Instruments and Hedging Activities - Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2023	Sep. 30, 2022
Fair Value of Assets
Gross amount recognized	$ 36	$ 54
Gross amount eligible for offsetting	(16)	(42)
Net amount	20	12
Fair Value of Liabilities
Gross amount recognized	3,455	3,138
Gross amount eligible for offsetting	(16)	(42)
Net amount	$ 3,439	$ 3,096

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