Off-Balance-Sheet Arrangements, Commitments and Contingencies (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	$ 821,165	$ 819,605
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	805,719	804,715
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	$ 15,446	$ 14,890