Derivative Financial Instruments - Balance Sheet Offsetting, Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivative Liabilities
Gross Amounts of Recognized Liabilities	$ 97,204	$ 108,581
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	97,204	108,581
Financial Instruments (Collateral)	(15,410)	(11,498)
Cash Collateral Pledged	(53,561)	(81,164)
Net Amount	28,233	15,919
Repurchase, securities lending, and similar arrangements
Securities Sold under Agreements to Repurchase, Gross	0	0
Securities Sold under Agreements to Repurchase, Asset	0	0
Securities Sold under Agreements to Repurchase	0	0
Financial Instruments (Collateral)	0	0
Cash Collateral Pledged	0	0
Net Amount	0	0
Total
Gross Amounts of Recognized Liabilities	97,204	108,581
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	97,204	108,581
Financial Instruments (Collateral)	(15,410)	(11,498)
Cash Collateral Pledged	(53,561)	(81,164)
Net Amount	28,233	15,919
Foreign exchange forwards
Derivative Liabilities
Gross Amounts of Recognized Liabilities	82,959	95,454
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	82,959	95,454
Financial Instruments (Collateral)	(14,638)	(10,997)
Cash Collateral Pledged	(41,113)	(69,110)
Net Amount	27,208	15,347
Client foreign currency options
Derivative Liabilities
Gross Amounts of Recognized Liabilities	1,713	1,187
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	1,713	1,187
Financial Instruments (Collateral)	(772)	(501)
Cash Collateral Pledged	0	(130)
Net Amount	941	556
Client interest rate derivatives
Derivative Liabilities
Gross Amounts of Recognized Liabilities	12,532	11,940
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	12,532	11,940
Financial Instruments (Collateral)	0	0
Cash Collateral Pledged	(12,448)	(11,924)
Net Amount	$ 84	$ 16