Loans - Loans Portfolio by Internal Risk Grading (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 1,321,221	$ 1,336,125	[1]
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	284,257	251,666
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	717,195	760,848
Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	93,031	123,147
Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	624,164	637,701
Commercial real estate | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	624,164	637,701
Residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	315,280	319,183
Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	207,256	209,326
Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	108,024	109,857
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,489	4,428
Consumer | Performing
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,489	4,415
Consumer | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	13
Pass | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	280,908	248,714
Pass | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	88,229	114,502
Pass | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	614,695	625,861
Pass | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	200,488	200,405
Pass | Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	107,053	107,705
Special Mention | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,353	1,763
Special Mention | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,625	7,114
Special Mention | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,602	6,914
Special Mention | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,194	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	996	1,189
Substandard | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,177	1,531
Substandard | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,867	4,926
Substandard | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,574	4,483
Substandard | Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	971	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.