Commitments and Contingencies - Commitments to Extend Credit and Letters of Credit (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Commitments to Extend Credit
Loan Commitments and Letters of Credit [Line Items]
Notional Amount	$ 340,976	$ 321,143	$ 335,587
Fair Value	0	0	0
Standby Letters of Credit
Loan Commitments and Letters of Credit [Line Items]
Notional Amount	3,164	4,466	4,016
Fair Value	$ 26	$ 12	$ 4
Minimum | Standby Letters of Credit
Loan Commitments and Letters of Credit [Line Items]
Loan commitments, fixed fee percent	1.00%
Maximum | Standby Letters of Credit
Loan Commitments and Letters of Credit [Line Items]
Loan commitments, fixed fee percent	3.00%