Commitments, Contingencies and Related Party Transactions (Credit-related Commitments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Credit Extensions
Loan commitments	$ 5,075,480	$ 5,077,869
Commercial letters of credit and SBLCs	$ 1,655,897	$ 1,525,613

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