Derivative Instruments and Hedging Activities - Schedule of Derivative Assets, Liabilities and the Effects of Offsetting (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Derivative assets:
Fair value of derivative instruments	$ 298	$ 2,418
Gross amounts offset in the balance sheet	(124)	(295)
Cash collateral received	(40)	(398)
Total derivative assets – net	134	1,725
Derivative liabilities:
Derivative instrument, Liabilities	276	515
Gross amounts offset in the balance sheet	124	295
Cash collateral pledged	53	7
Total derivative liabilities – net	(99)	(213)
Foreign currency contracts
Derivative assets:
Fair value of derivative instruments	38	119
Derivative liabilities:
Derivative instrument, Liabilities	2	2
Interest rate contracts
Derivative assets:
Fair value of derivative instruments	28	66
Commodity contract - subject to PGC and DS mechanisms
Derivative assets:
Fair value of derivative instruments	6	31
Derivative liabilities:
Derivative instrument, Liabilities	8	26
Commodity contracts
Derivative assets:
Fair value of derivative instruments	232	2,233
Derivative liabilities:
Derivative instrument, Liabilities	274	513
Derivatives designated as hedging instruments
Derivative assets:
Fair value of derivative instruments	42	123
Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative assets:
Fair value of derivative instruments	14	57
Derivatives designated as hedging instruments \| Interest rate contracts
Derivative assets:
Fair value of derivative instruments	28	66
Derivatives not designated as hedging instruments
Derivative assets:
Fair value of derivative instruments	250	2,264
Derivative liabilities:
Derivative instrument, Liabilities	268	489
Derivatives not designated as hedging instruments \| Foreign currency contracts
Derivative assets:
Fair value of derivative instruments	24	62
Derivative liabilities:
Derivative instrument, Liabilities	2	2
Derivatives not designated as hedging instruments \| Commodity contracts
Derivative assets:
Fair value of derivative instruments	226	2,202
Derivative liabilities:
Derivative instrument, Liabilities	266	487
Derivatives not designated as hedging instruments \| Commodity contracts \| Held for sale assets
Derivative assets:
Fair value of derivative instruments	10	295
Derivatives not designated as hedging instruments \| Commodity contracts \| Held for sale liabilities
Derivative liabilities:
Derivative instrument, Liabilities	$ 12	$ 19

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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