Commitments, Contingencies and Guarantees - Notional Amount of Off-Balance Sheet Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Commitments to extend credit for loans (excluding credit card loans) [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	$ 8,426,630	$ 7,409,338
Commitments to extend credit under credit card loans [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	3,378,292	3,188,905
Commercial letters of credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	3,301	4,460
Standby letters of credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	339,065	299,933
Forward contracts [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	230,441	58,287
Spot foreign exchange contracts [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	$ 2,384	$ 1,980