Derivative Financial Instruments - Company's derivative financial instruments included in OCI as follows (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain in OCI on derivatives	$ 0	$ 43,556
Gain reclassified from OCI into interest income (effective portion)	8,274	3,112
Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness test)	0	0
Gain (loss) recognized in other income for foreign currency exchange contracts:	5,299	(6,210)
Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Gain reclassified from OCI into interest income (effective portion)	8,274	3,112
Interest Income | Net Investment Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness test)	0	0
Interest Income | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) recognized in interest rate swap income	4,851	(6,280)
Interest Income | Risk participation agreements
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) recognized in interest rate swap income	369	(301)
Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness test)	0	0
Other Income | Foreign currency exchange contracts - matched customer book
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other income for foreign currency exchange contracts:	6	(26)
Other Income | Foreign currency exchange contracts - foreign currency loan
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other income for foreign currency exchange contracts:	$ 73	$ 397