Loans - Loans Portfolio by Internal Risk Grading (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 1,331,153	$ 1,336,125	[1]
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	284,176	251,666
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	731,568	760,848
Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	99,546	123,147
Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	632,022	637,701
Commercial real estate | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	632,022	637,701
Residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	310,150	319,183
Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	205,277	209,326
Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	104,873	109,857
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,259	4,428
Consumer | Performing
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,259	4,415
Consumer | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	13
Pass | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	281,211	248,714
Pass | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	95,662	114,502
Pass | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	623,317	625,861
Pass | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	199,205	200,405
Pass | Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	104,313	107,705
Special Mention | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,588	1,763
Special Mention | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,870	7,114
Special Mention | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,333	6,914
Special Mention | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,046	4,438
Special Mention | Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	1,325
Substandard | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,377	1,189
Substandard | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,014	1,531
Substandard | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,372	4,926
Substandard | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,026	4,483
Substandard | Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	560	827
Doubtful | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Doubtful | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Doubtful | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Doubtful | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Doubtful | Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 0	$ 0

[1] Derived from audited consolidated financial statements.