Loans and Allowance for Loan Losses - Impaired Loans (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) item	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	$ 7,652		$ 7,652		$ 2,799
Impaired Loans with Specific Allowance, Related Allowance	930		930		690
Impaired Loans with No Specific Allowance, Recorded Investment	5,267		5,267		11,982
Total Impaired Loans, Recorded Investment	12,919		12,919		14,781
Total Impaired Loans, Unpaid Principal Balance	14,594		$ 14,594		15,856
Impaired loans, additional information
Number of loans causing change in impaired loans | item			3
Financing Receivable, Allowance for Credit Losses, Write-downs	304	$ 665	$ 727	$ 776
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	13,365	7,235	13,935	7,321
Interest income recognized on an accrual basis on impaired loans	61	38	184	230
Interest income recognized on a cash basis on impaired loans	60	17	170	157
Total Recorded Investment in Impaired Financing Receivables [Member] | Credit Concentration Risk [Member]
Impaired loans by class
Total Impaired Loans, Recorded Investment	7,800		$ 7,800
Impaired loans, additional information
Number of loans causing change in impaired loans | item			2
Concentration Risk, Percentage			60.00%
Total Recorded Investment in Impaired Financing Receivables [Member] | Government Contracts Concentration Risk [Member]
Impaired loans by class
Total Impaired Loans, Recorded Investment	5,000		$ 5,000
Impaired loans, additional information
Number of loans causing change in impaired loans | item			1
Commercial
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	6,791		$ 6,791		1,800
Impaired Loans with Specific Allowance, Related Allowance	595		595		362
Impaired Loans with No Specific Allowance, Recorded Investment	5,245		5,245		11,982
Total Impaired Loans, Recorded Investment	12,036		12,036		13,782
Total Impaired Loans, Unpaid Principal Balance	13,711		13,711		14,857
Impaired loans, additional information
Financing Receivable, Allowance for Credit Losses, Write-downs	299	634	708	632
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	12,427	6,323	12,971	6,489
Interest income recognized on an accrual basis on impaired loans	56	33	168	213
Interest income recognized on a cash basis on impaired loans	53	12	158	142
Impaired loans, recorded investment, in process of foreclosure	249		249
Commercial Business
Impaired loans by class
Impaired Loans with No Specific Allowance, Recorded Investment	2,758		2,758		3,606
Total Impaired Loans, Recorded Investment	2,758		2,758		3,606
Total Impaired Loans, Unpaid Principal Balance	2,758		2,758		3,606
Impaired loans, additional information
Proceeds from Collection of Loans Receivable			848
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	2,945		3,228
Interest income recognized on an accrual basis on impaired loans	39		117
Interest income recognized on a cash basis on impaired loans	39		114
Commercial Real Estate
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	6,522		6,522		1,527
Impaired Loans with Specific Allowance, Related Allowance	498		498		260
Impaired Loans with No Specific Allowance, Recorded Investment					5,021
Total Impaired Loans, Recorded Investment	6,522		6,522		6,548
Total Impaired Loans, Unpaid Principal Balance	6,522		6,522		6,548
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	6,525	1,740	6,533	1,854
Interest income recognized on an accrual basis on impaired loans	15	31	44	94
Interest income recognized on a cash basis on impaired loans	12	8	37	50
Acquisition & Development
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	269		269		273
Impaired Loans with Specific Allowance, Related Allowance	97		97		102
Impaired Loans with No Specific Allowance, Recorded Investment	2,487		2,487		3,355
Total Impaired Loans, Recorded Investment	2,756		2,756		3,628
Total Impaired Loans, Unpaid Principal Balance	4,431		4,431		4,703
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	2,957	4,583	3,210	4,635
Interest income recognized on an accrual basis on impaired loans	2	2	7	119
Interest income recognized on a cash basis on impaired loans	2	4	7	92
Two Unrelated Acquisition and Development Loans [Member]
Impaired loans by class
Total Impaired Loans, Recorded Investment	2,200		$ 2,200		3,100
Impaired loans, additional information
Number of loans causing change in impaired loans | item			2
Financing Receivable, Principal Curtailment			$ 268
Financing Receivable, Allowance for Credit Losses, Write-downs			600
Residential
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	827		827		969
Impaired Loans with Specific Allowance, Related Allowance	301		301		298
Impaired Loans with No Specific Allowance, Recorded Investment	22		22
Total Impaired Loans, Recorded Investment	849		849		969
Total Impaired Loans, Unpaid Principal Balance	849		849		969
Impaired loans, additional information
Financing Receivable, Allowance for Credit Losses, Write-downs		30	14	133
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	909	868	935	779
Interest income recognized on an accrual basis on impaired loans	5	5	15	15
Interest income recognized on a cash basis on impaired loans	7	5	11	14
Home Equity
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	28		28		28
Impaired Loans with Specific Allowance, Related Allowance	28		28		28
Total Impaired Loans, Recorded Investment	28		28		28
Total Impaired Loans, Unpaid Principal Balance	28		28		28
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	28	28	28	28
Interest income recognized on an accrual basis on impaired loans			1	1
Interest income recognized on a cash basis on impaired loans			1
Consumer
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	6		6		2
Impaired Loans with Specific Allowance, Related Allowance	6		6		2
Total Impaired Loans, Recorded Investment	6		6		2
Total Impaired Loans, Unpaid Principal Balance	6		6		$ 2
Impaired loans, additional information
Financing Receivable, Allowance for Credit Losses, Write-downs	5	1	5	11
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	$ 1	$ 16	$ 1	25
Interest income recognized on an accrual basis on impaired loans				1
Interest income recognized on a cash basis on impaired loans				$ 1