Commitments and Contingencies (Credit-Related Commitments) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Loan commitments	$ 5,349,316	$ 5,147,821
Commercial letters of credit and SBLCs	$ 1,806,083	$ 1,796,647

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant