Derivative Financial Instruments - Summary of Fair Values of Derivative Instruments in the Company's Unaudited Consolidated Balance Sheets (Details) - Loan Related Derivative Contracts - Derivatives Not Designated as Hedging Instruments - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative assets	$ 3,551	$ 1,859
Derivative liabilities	3,592	1,940
Interest Rate Swap Contracts
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative assets	3,551	1,859
Mirror Swaps with Counterparties
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative liabilities	3,551	1,859
Risk Participation Agreements
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative liabilities	$ 41	$ 81