Loans - Loans Portfolio by Internal Risk Grading (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 1,804,447	$ 1,357,476	[1]
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	324,508	285,972
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,027,007	753,040
Commercial real estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	143,788	97,240
Commercial real estate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	883,219	655,800
Commercial real estate | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	883,219	655,800
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	440,907	313,371
Residential | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	318,833	209,438
Residential | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	122,074	103,933
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	12,025	5,093
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	12,025	5,093
Consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	0	0
Pass | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	310,172	285,092
Pass | Commercial real estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	135,296	93,000
Pass | Commercial real estate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	835,255	647,519
Pass | Residential | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	304,644	204,261
Pass | Residential | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	121,531	103,541
Special Mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	12,614	154
Special Mention | Commercial real estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	5,851	1,840
Special Mention | Commercial real estate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	35,415	4,403
Special Mention | Residential | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	9,189	1,685
Special Mention | Residential | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	0	0
Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,722	726
Substandard | Commercial real estate | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	2,641	2,400
Substandard | Commercial real estate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	12,549	3,878
Substandard | Residential | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	5,000	3,492
Substandard | Residential | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	543	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 | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	0	0
Doubtful | Residential | Real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	0	0
Doubtful | Residential | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 0	$ 0

[1] Derived from audited consolidated financial statements.