Loans - Past Due (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	$ 3,833	$ 5,438
90 Days Plus Past Due and Still Accruing	538	587
Non- Accrual Loans	2,498	2,965
Current	1,291,321	1,159,383
Total Loans	1,295,154	1,164,821	[1]
Commercial
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	185	69
90 Days Plus Past Due and Still Accruing	0	0
Non- Accrual Loans	143	19
Current	230,299	208,648
Total Loans	230,484	208,717
Commercial real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Loans	740,303	625,218
Commercial real estate | Construction and land development
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	58	136
90 Days Plus Past Due and Still Accruing	0	0
Non- Accrual Loans	58	64
Current	137,811	114,122
Total Loans	137,869	114,258
Commercial real estate | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	1,354	1,239
90 Days Plus Past Due and Still Accruing	279	339
Non- Accrual Loans	803	773
Current	601,080	509,721
Total Loans	602,434	510,960
Residential
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Loans	320,127	325,855
Residential | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	1,956	3,447
90 Days Plus Past Due and Still Accruing	259	248
Non- Accrual Loans	1,244	1,802
Current	207,245	211,657
Total Loans	209,201	215,104
Residential | Home equity
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	271	518
90 Days Plus Past Due and Still Accruing	0	0
Non- Accrual Loans	249	289
Current	110,655	110,233
Total Loans	110,926	110,751
Consumer
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	9	29
90 Days Plus Past Due and Still Accruing	0	0
Non- Accrual Loans	1	18
Current	4,231	5,002
Total Loans	4,240	5,031
30- 59 Days Past Due
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	281	1,625
30- 59 Days Past Due | Commercial
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	22	50
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	60
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	33	0
30- 59 Days Past Due | Residential | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	196	1,280
30- 59 Days Past Due | Residential | Home equity
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	22	229
30- 59 Days Past Due | Consumer
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	8	6
60-89 Days Past Due
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	516	261
60-89 Days Past Due | Commercial
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	20	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	12
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	239	127
60-89 Days Past Due | Residential | Real estate
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	257	117
60-89 Days Past Due | Residential | Home equity
Analysis by portfolio segment of the entity's past due loans [Abstract]
Total Past Due	0	0
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.