Loans and Allowance for Loan Losses - Internal Risk Rating Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	$ 1,094,467	$ 1,052,865	$ 1,076,073
Commercial
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	782,863	757,516	750,044
Commercial | Commercial Business
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	365,710	387,466
Commercial | Commercial Real Estate
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	297,603	271,460
Commercial | Acquisition & Development
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	119,550	98,590
Residential
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	234,236	215,452	243,487
Home Equity
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	64,273	65,386	67,839
Consumer
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	13,095	14,511	$ 14,703
Pass
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	1,043,783	1,001,066
Pass | Commercial
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	736,493	709,357
Pass | Commercial | Commercial Business
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	356,809	377,631
Pass | Commercial | Commercial Real Estate
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	266,798	240,851
Pass | Commercial | Acquisition & Development
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	112,886	90,875
Pass | Residential
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	231,434	212,869
Pass | Home Equity
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	63,102	64,706
Pass | Consumer
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	12,754	14,134
Special Mention
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	32,003	33,726
Special Mention | Commercial
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	28,486	31,178
Special Mention | Commercial | Commercial Business
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	4,348	2,933
Special Mention | Commercial | Commercial Real Estate
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	23,198	26,340
Special Mention | Commercial | Acquisition & Development
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	940	1,905
Special Mention | Residential
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	2,291	1,664
Special Mention | Home Equity
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	1,043	582
Special Mention | Consumer
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	183	302
Substandard
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	15,949	13,847
Substandard | Commercial
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	15,563	12,949
Substandard | Commercial | Commercial Business
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	4,553	6,833
Substandard | Commercial | Commercial Real Estate
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	7,607	3,532
Substandard | Commercial | Acquisition & Development
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	3,403	2,584
Substandard | Residential
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	231	787
Substandard | Home Equity
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	128	98
Substandard | Consumer
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	27	13
Doubtful
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	2,732	4,226
Doubtful | Commercial
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	2,321	4,032
Doubtful | Commercial | Commercial Business
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	0	69
Doubtful | Commercial | Commercial Real Estate
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	0	737
Doubtful | Commercial | Acquisition & Development
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	2,321	3,226
Doubtful | Residential
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	280	132
Doubtful | Home Equity
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	0	0
Doubtful | Consumer
Classes of the loan portfolio summarized by credit quality indicators:
Total loans	$ 131	$ 62