Loans and Allowance for Loan Losses - Aging (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Aging categories of performing loans and nonaccrual loans
Current	$ 1,143,201	$ 1,095,474
Total Past Due	13,372	9,832
Total Loans	1,156,573	1,105,306	$ 1,075,868
Non-Accrual	9,102	9,699
90 Plus Days Still Accruing	0	0
Commercial
Aging categories of performing loans and nonaccrual loans
Current	816,661	777,756
Total Past Due	7,964	6,153
Total Loans	824,625	783,909	752,331
Non-Accrual	7,714	8,350
90 Plus Days Still Accruing	0	0
Commercial | Commercial Business
Aging categories of performing loans and nonaccrual loans
Current	387,428	377,901
Total Past Due	2,018	2,462
Total Loans	389,446	380,363
Non-Accrual	1,758	1,027
90 Plus Days Still Accruing	0	0
Commercial | Commercial Real Estate
Aging categories of performing loans and nonaccrual loans
Current	321,198	300,282
Total Past Due	4,654	1,574
Total Loans	325,852	301,856
Non-Accrual	4,664	5,206
90 Plus Days Still Accruing	0	0
Commercial | Acquisition & Development
Aging categories of performing loans and nonaccrual loans
Current	108,035	99,573
Total Past Due	1,292	2,117
Total Loans	109,327	101,690
Non-Accrual	1,292	2,117
90 Plus Days Still Accruing	0	0
Residential
Aging categories of performing loans and nonaccrual loans
Current	255,659	243,177
Total Past Due	4,854	3,037
Total Loans	260,513	246,214	244,606
Non-Accrual	1,301	1,157
90 Plus Days Still Accruing	0	0
Home Equity
Aging categories of performing loans and nonaccrual loans
Current	59,050	61,907
Total Past Due	476	493
Total Loans	59,526	62,400	65,170
Non-Accrual	44	13
90 Plus Days Still Accruing	0	0
Consumer
Aging categories of performing loans and nonaccrual loans
Current	11,831	12,634
Total Past Due	78	149
Total Loans	11,909	12,783	$ 13,761
Non-Accrual	43	179
90 Plus Days Still Accruing	0	0
Financing Receivables, 30 to 59 Days Past Due
Aging categories of performing loans and nonaccrual loans
Total Past Due	7,160	2,687
Financing Receivables, 30 to 59 Days Past Due | Commercial
Aging categories of performing loans and nonaccrual loans
Total Past Due	2,521	557
Financing Receivables, 30 to 59 Days Past Due | Commercial | Commercial Business
Aging categories of performing loans and nonaccrual loans
Total Past Due	473	512
Financing Receivables, 30 to 59 Days Past Due | Commercial | Commercial Real Estate
Aging categories of performing loans and nonaccrual loans
Total Past Due	1,188	45
Financing Receivables, 30 to 59 Days Past Due | Commercial | Acquisition & Development
Aging categories of performing loans and nonaccrual loans
Total Past Due	860	0
Financing Receivables, 30 to 59 Days Past Due | Residential
Aging categories of performing loans and nonaccrual loans
Total Past Due	4,417	1,879
Financing Receivables, 30 to 59 Days Past Due | Home Equity
Aging categories of performing loans and nonaccrual loans
Total Past Due	194	240
Financing Receivables, 30 to 59 Days Past Due | Consumer
Aging categories of performing loans and nonaccrual loans
Total Past Due	28	11
Financing Receivables, 60 to 89 Days Past Due
Aging categories of performing loans and nonaccrual loans
Total Past Due	802	4,338
Financing Receivables, 60 to 89 Days Past Due | Commercial
Aging categories of performing loans and nonaccrual loans
Total Past Due	393	3,391
Financing Receivables, 60 to 89 Days Past Due | Commercial | Commercial Business
Aging categories of performing loans and nonaccrual loans
Total Past Due	393	1,368
Financing Receivables, 60 to 89 Days Past Due | Commercial | Commercial Real Estate
Aging categories of performing loans and nonaccrual loans
Total Past Due	0	1,149
Financing Receivables, 60 to 89 Days Past Due | Commercial | Acquisition & Development
Aging categories of performing loans and nonaccrual loans
Total Past Due	0	874
Financing Receivables, 60 to 89 Days Past Due | Residential
Aging categories of performing loans and nonaccrual loans
Total Past Due	108	707
Financing Receivables, 60 to 89 Days Past Due | Home Equity
Aging categories of performing loans and nonaccrual loans
Total Past Due	282	240
Financing Receivables, 60 to 89 Days Past Due | Consumer
Aging categories of performing loans and nonaccrual loans
Total Past Due	19	0
Financing Receivables, Equal to Greater than 90 Days Past Due
Aging categories of performing loans and nonaccrual loans
Total Past Due	5,410	2,807
Financing Receivables, Equal to Greater than 90 Days Past Due | Commercial
Aging categories of performing loans and nonaccrual loans
Total Past Due	5,050	2,205
Financing Receivables, Equal to Greater than 90 Days Past Due | Commercial | Commercial Business
Aging categories of performing loans and nonaccrual loans
Total Past Due	1,152	582
Financing Receivables, Equal to Greater than 90 Days Past Due | Commercial | Commercial Real Estate
Aging categories of performing loans and nonaccrual loans
Total Past Due	3,466	380
Financing Receivables, Equal to Greater than 90 Days Past Due | Commercial | Acquisition & Development
Aging categories of performing loans and nonaccrual loans
Total Past Due	432	1,243
Financing Receivables, Equal to Greater than 90 Days Past Due | Residential
Aging categories of performing loans and nonaccrual loans
Total Past Due	329	451
Financing Receivables, Equal to Greater than 90 Days Past Due | Home Equity
Aging categories of performing loans and nonaccrual loans
Total Past Due	0	13
Financing Receivables, Equal to Greater than 90 Days Past Due | Consumer
Aging categories of performing loans and nonaccrual loans
Total Past Due	$ 31	$ 138