Loans - Credit exposure (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 1,830,815	$ 1,357,476
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	339,077	285,972
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	1,037,119	753,040
Commercial Real Estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	137,920	97,240
Commercial Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	899,199	655,800
Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	443,738	313,371
Residential Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	324,315	209,438
Residential Real Estate | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	119,423	103,933
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	10,881	5,093
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	10,877	5,093
Consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	4	0
Pass | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	328,488	285,092
Pass | Commercial Real Estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	130,694	93,000
Pass | Commercial Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	860,615	647,519
Pass | Residential Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	316,454	204,261
Pass | Residential Real Estate | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	118,960	103,541
Special Mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	8,710	154
Special Mention | Commercial Real Estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	4,133	1,840
Special Mention | Commercial Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	22,117	4,403
Special Mention | Residential Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	4,370	1,685
Special Mention | Residential Real Estate | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	1,879	726
Substandard | Commercial Real Estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	3,093	2,400
Substandard | Commercial Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	16,467	3,878
Substandard | Residential Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	3,491	3,492
Substandard | Residential Real Estate | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	463	392
Doubtful | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Doubtful | Commercial Real Estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Doubtful | Commercial Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Doubtful | Residential Real Estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Doubtful | Residential Real Estate | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 0	$ 0