Commitments, Contingencies and Guarantees - Notional Amount of Off-Balance Sheet Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 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	$ 7,254,024	$ 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	3,285,687	3,188,905
Commercial letters of credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	5,320	4,460
Standby letters of credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	301,416	299,933
Forward contracts [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	218,750	58,287
Spot foreign exchange contracts [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract or notional amount of off-balance sheet financial instruments	$ 4,375	$ 1,980