Derivative Instruments - Additional Information (Details) $ in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2022 CAD ($)	Oct. 01, 2022 USD ($)	Oct. 01, 2022 CAD ($)
Derivative [Line Items]
Net deferred gains recorded in AOCI for contracts that will mature in the next twelve months	$ 317
Hedging Period for Foreign Currency Transactions, Maximum	4 years
Aggregate fair value of derivative instruments with credit-risk-related contingent features in a net liability position by counterparty	$ 1,700		$ 1,500
Derivatives designated as hedges | Interest rate | Fair Value Hedging
Derivative [Line Items]
Derivative, Notional Amount	13,500		14,500
Derivatives designated as hedges | Foreign exchange | Cash Flow Hedging
Derivative [Line Items]
Derivative, Notional Amount	7,300		7,400
Derivatives designated as hedges | Currency Swap | Fair Value Hedging
Derivative [Line Items]
Derivative, Notional Amount	1,000	$ 1,300	900	$ 1,300
Not Designated as Hedging Instrument | Foreign exchange
Derivative [Line Items]
Derivative, Notional Amount	4,200		3,800
Not Designated as Hedging Instrument | Other Derivative
Derivative [Line Items]
Derivative, Notional Amount	$ 400		$ 400