Unsecured Borrowings - Subordinated Borrowings (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total subordinated Borrowings, par amount	$ 13,113	$ 13,229
Total subordinated Borrowings	$ 11,895	$ 12,936
Rate	7.60%	6.29%
Subordinated debt
Debt Instrument [Line Items]
Subordinated debt, par amount	$ 12,145	$ 12,261
Subordinated debt outstanding	$ 10,910	$ 11,882
Rate	7.70%	6.40%
Junior subordinated debt
Debt Instrument [Line Items]
Subordinated debt, par amount	$ 968	$ 968
Junior subordinated debt	$ 985	$ 1,054
Rate	6.35%	4.86%