Loans - Credit exposure (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 1,357,476	$ 1,336,125
Threshold limit to consider loan as nonperforming	90 days
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 285,972	251,666
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	753,040	760,848
Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	97,240	123,147
Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	655,800	637,701
Commercial real estate | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	655,800	637,701
Residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	313,371	319,183
Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	209,438	209,326
Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	103,933	109,857
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,093	4,428
Consumer | Performing
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,093	4,415
Consumer | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	13
Pass | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	285,092	248,714
Pass | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	93,000	114,502
Pass | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	647,519	625,861
Pass | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	204,261	200,405
Pass | Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	103,541	107,705
Special Mention | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	154	1,763
Special Mention | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,840	7,114
Special Mention | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,403	6,914
Special Mention | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,685	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	726	1,189
Substandard | Commercial real estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,400	1,531
Substandard | Commercial real estate | Other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,878	4,926
Substandard | Residential | Real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,492	4,483
Substandard | Residential | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total Loans	392	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