Loan Servicing - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	$ 6,248		$ 6,248		$ 5,957
Servicing fees net of servicing asset amortization	137	$ 314	164	$ 571
Mortgage Loans
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	3,100		3,100		2,500
SBA Loans
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	$ 5,500		$ 5,500		$ 5,900