Loans - Past Due (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	$ 3,004	$ 3,274
90 Days Past Due and Still Accruing	74	359
Non- Accrual Loans	2,238	2,201
Current	1,328,149	1,332,851
Total Loans	1,331,153	1,336,125	[1]
Commercial
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	1,061	182
90 Days Past Due and Still Accruing	0	0
Non- Accrual Loans	1,054	90
Current	283,115	251,484
Total Loans	284,176	251,666
Commercial real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Loans	731,568	760,848
Commercial real estate | Construction and land development
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	30	36
90 Days Past Due and Still Accruing	0	0
Non- Accrual Loans	30	36
Current	99,516	123,111
Total Loans	99,546	123,147
Commercial real estate | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	260	855
90 Days Past Due and Still Accruing	0	280
Non- Accrual Loans	215	489
Current	631,762	636,846
Total Loans	632,022	637,701
Residential
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Loans	310,150	319,183
Residential | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	1,365	1,775
90 Days Past Due and Still Accruing	74	79
Non- Accrual Loans	795	1,343
Current	203,912	207,551
Total Loans	205,277	209,326
Residential | Home equity
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	273	400
90 Days Past Due and Still Accruing	0	0
Non- Accrual Loans	144	243
Current	104,600	109,457
Total Loans	104,873	109,857
Consumer
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	15	26
90 Days Past Due and Still Accruing	0	0
Non- Accrual Loans	0	0
Current	5,244	4,402
Total Loans	5,259	4,428
30- 59 Days Past Due
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	265	622
30- 59 Days Past Due | Commercial
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	7	92
30- 59 Days Past Due | Commercial real estate | Construction and land development
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	0	0
30- 59 Days Past Due | Commercial real estate | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	45	86
30- 59 Days Past Due | Residential | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	69	282
30- 59 Days Past Due | Residential | Home equity
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	129	141
30- 59 Days Past Due | Consumer
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	15	21
60-89 Days Past Due
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	427	92
60-89 Days Past Due | Commercial
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	0	0
60-89 Days Past Due | Commercial real estate | Construction and land development
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	0	0
60-89 Days Past Due | Commercial real estate | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	0	0
60-89 Days Past Due | Residential | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	427	71
60-89 Days Past Due | Residential | Home equity
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	0	16
60-89 Days Past Due | Consumer
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	$ 0	$ 5

[1] Derived from audited consolidated financial statements.