Loans - Aging of Past Due Loans by Class of Loans - Tabular Disclosure (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Aging of Past Due Loans by Class of Loans
Total Past Due	$ 8,873	$ 6,943
Loans Not Past Due	1,877,859	1,576,234
Total loan balance	1,886,732	1,583,177
30-59 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	5,699	4,511
60-89 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	1,916	1,224
90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	1,258	1,208
Commercial
Aging of Past Due Loans by Class of Loans
Total Past Due	8,872
Loans Not Past Due	588,891
Total loan balance	597,763	573,296
Commercial | 30-59 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	5,698
Commercial | 60-89 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	1,916
Commercial | 90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	1,258
Real estate
Aging of Past Due Loans by Class of Loans
Total loan balance	1,276,516	997,486
Consumer
Aging of Past Due Loans by Class of Loans
Total Past Due	1
Loans Not Past Due	12,452	12,395
Total loan balance	12,453	12,395
Consumer | 30-59 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	1
Commercial
Aging of Past Due Loans by Class of Loans
Total Past Due		6,101
Loans Not Past Due		567,195
Total loan balance		573,296
Commercial | 30-59 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due		4,288
Commercial | 60-89 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due		1,224
Commercial | 90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due		589
CRE | Real estate
Aging of Past Due Loans by Class of Loans
Total Past Due		500
Loans Not Past Due	994,067	772,367
Total loan balance	994,067	772,867
CRE | Real estate | 90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due		500
Land and construction | Real estate
Aging of Past Due Loans by Class of Loans
Total Past Due		119
Loans Not Past Due	122,358	100,763
Total loan balance	122,358	100,882
Land and construction | Real estate | 90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due		119
Home equity | Real estate
Aging of Past Due Loans by Class of Loans
Total Past Due		223
Loans Not Past Due	109,112	78,953
Total loan balance	109,112	79,176
Home equity | Real estate | 30-59 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due		223
Residential mortgages | Real estate
Aging of Past Due Loans by Class of Loans
Loans Not Past Due	50,979	44,561
Total loan balance	$ 50,979	$ 44,561