Commitments, Contingencies and Guarantees - Notional Amount of Off-Balance Sheet Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Commitments to extend credit for loans (excluding credit card loans) [Member]
Commitments and Contingencies Disclosure [Line Items]
Contractual or notional amount of off-balance sheet financial instruments	$ 19,134,503	$ 17,819,711
Commitments to extend credit under credit card loans [Member]
Commitments and Contingencies Disclosure [Line Items]
Contractual or notional amount of off-balance sheet financial instruments	5,207,847	5,994,640
Commercial letters of credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Contractual or notional amount of off-balance sheet financial instruments	741	217
Standby letters of credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Contractual or notional amount of off-balance sheet financial instruments	486,493	468,384
Forward contracts [Member]
Commitments and Contingencies Disclosure [Line Items]
Contractual or notional amount of off-balance sheet financial instruments	152,152	119,978
Spot foreign exchange contracts [Member]
Commitments and Contingencies Disclosure [Line Items]
Contractual or notional amount of off-balance sheet financial instruments	14,808	34,233
Commitments to extend credit for securities purchased under agreements to resell [Member]
Commitments and Contingencies Disclosure [Line Items]
Contractual or notional amount of off-balance sheet financial instruments	$ 886,000	$ 191,000