Guarantees and Contingent Liabilities - Summary of Other Guarantees and Contingent Liabilities (Detail) $ in Millions	Sep. 30, 2022 USD ($)
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Collateral Held	$ 0
Carrying Amount	53
Maximum Potential Future Payments	9,974
Third Party Borrowing Arrangements [Member]
Guarantor Obligations [Line Items]
Collateral Held	0
Carrying Amount	0
Maximum Potential Future Payments	10
Securities Lending Indemnifications [Member]
Guarantor Obligations [Line Items]
Collateral Held	6,869
Carrying Amount	0
Maximum Potential Future Payments	6,625
Asset Sales [Member]
Guarantor Obligations [Line Items]
Collateral Held	0	[1]
Carrying Amount	89	[1]
Maximum Potential Future Payments	7,616	[1]
Merchant Processing [Member]
Guarantor Obligations [Line Items]
Collateral Held	727
Carrying Amount	123
Maximum Potential Future Payments	139,808
Tender Option Bond Program Guarantee [Member]
Guarantor Obligations [Line Items]
Collateral Held	1,418
Carrying Amount	0
Maximum Potential Future Payments	1,497
Other Guarantees [Member]
Guarantor Obligations [Line Items]
Collateral Held	0
Carrying Amount	21
Maximum Potential Future Payments	$ 2,081

[1] The maximum potential future payments do not include loan sales where the Company provides standard representation and warranties to the buyer against losses related to loan underwriting documentation defects that may have existed at the time of sale that generally are identified after the occurrence of a triggering event such as delinquency. For these types of loan sales, the maximum potential future payments is generally the unpaid principal balance of loans sold measured at the end of the current reporting period. Actual losses will be significantly less than the maximum exposure, as only a fraction of loans sold will have a representation and warranty breach, and any losses on repurchase would generally be mitigated by any collateral held against the loans.