Commitments and Contingencies (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Credit Extensions
Loan commitments	$ 4,956,515	$ 5,077,869
Commercial letters of credit and SBLCs	1,757,648	1,525,613
Commercial Letters of Credit
Credit Extensions
Commercial letters of credit and SBLCs	59,100
Standby Letters of Credit
Credit Extensions
Commercial letters of credit and SBLCs	1,700,000
Accrued Expenses and Other Liabilities
Credit Extensions
Allowance for unfunded credit reserves	$ 14,000	$ 15,700