Commitments and Contingent Liabilities - Summary of Commitments and Contingent Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Commitments to Grant Loans
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Commitments to grant loans	$ 103,570	$ 522,967
Standby Letters of Credit
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Letters of credit	141,214	101,718
Performance Letters of Credit
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Performance letters of credit	21,026	17,638
Commercial Letters of Credit
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Letters of credit	11,262	11,790
Commitments to Extend Credit
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Commitments to extend credit	$ 4,078,708	$ 3,270,097