Loans and Allowance for Loan Losses - Impaired Loans (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) item	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) item	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	$ 7,736		$ 7,736		$ 2,799
Impaired Loans with Specific Allowance, Related Allowance	943		943		690
Impaired Loans with No Specific Allowance, Recorded Investment	5,938		5,938		11,982
Total Impaired Loans, Recorded Investment	13,674		13,674		14,781
Total Impaired Loans, Unpaid Principal Balance	15,039		$ 15,039		15,856
Impaired loans, additional information
Number of loans causing change in impaired loans | item			3
Financing Receivable, Allowance for Credit Losses, Write-downs		$ 104	$ 423	$ 111
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	13,883	7,660	14,222	7,364
Interest income recognized on an accrual basis on impaired loans	61	78	123	159
Interest income recognized on a cash basis on impaired loans	53	89	107	125
Total Recorded Investment in Impaired Financing Receivables [Member] | Credit Concentration Risk [Member]
Impaired loans by class
Total Impaired Loans, Recorded Investment	8,100		$ 8,100
Impaired loans, additional information
Number of loans causing change in impaired loans | item			2
Concentration Risk, Percentage			59.00%
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	6,801		$ 6,801		1,800
Impaired Loans with Specific Allowance, Related Allowance	605		605		362
Impaired Loans with No Specific Allowance, Recorded Investment	5,826		5,826		11,982
Total Impaired Loans, Recorded Investment	12,627		12,627		13,782
Total Impaired Loans, Unpaid Principal Balance	14,002		14,002		14,857
Impaired loans, additional information
Financing Receivable, Allowance for Credit Losses, Write-downs			409
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	12,908	6,732	13,244	6,572
Interest income recognized on an accrual basis on impaired loans	56	73	112	147
Interest income recognized on a cash basis on impaired loans	$ 53	84	$ 104	116
Number of loans, in process of foreclosure | item	5		5
Impaired loans, recorded investment, in process of foreclosure	$ 420		$ 420
Commercial Business
Impaired loans by class
Impaired Loans with No Specific Allowance, Recorded Investment	3,039		3,039		3,606
Total Impaired Loans, Recorded Investment	3,039		3,039		3,606
Total Impaired Loans, Unpaid Principal Balance	3,039		3,039		3,606
Impaired loans, additional information
Proceeds from Collection of Loans Receivable			567
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	3,228		3,369
Interest income recognized on an accrual basis on impaired loans	39		78
Interest income recognized on a cash basis on impaired loans	39		75
Commercial Real Estate
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	6,530		6,530		1,527
Impaired Loans with Specific Allowance, Related Allowance	507		507		260
Impaired Loans with No Specific Allowance, Recorded Investment					5,021
Total Impaired Loans, Recorded Investment	6,530		6,530		6,548
Total Impaired Loans, Unpaid Principal Balance	6,530		6,530		6,548
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	6,533	1,907	6,538	1,911
Interest income recognized on an accrual basis on impaired loans	15	15	30	30
Interest income recognized on a cash basis on impaired loans	12	15	25	35
Acquisition & Development
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	271		271		273
Impaired Loans with Specific Allowance, Related Allowance	98		98		102
Impaired Loans with No Specific Allowance, Recorded Investment	2,787		2,787		3,355
Total Impaired Loans, Recorded Investment	3,058		3,058		3,628
Total Impaired Loans, Unpaid Principal Balance	4,433		4,433		4,703
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	3,147	4,825	3,337	4,661
Interest income recognized on an accrual basis on impaired loans	2	58	4	117
Interest income recognized on a cash basis on impaired loans	2	69	4	81
Two Unrelated Acquisition and Development Loans [Member]
Impaired loans by class
Total Impaired Loans, Recorded Investment	2,500		$ 2,500		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			300
Residential
Impaired loans by class
Impaired Loans with Specific Allowance, Recorded Investment	900		900		969
Impaired Loans with Specific Allowance, Related Allowance	303		303		298
Impaired Loans with No Specific Allowance, Recorded Investment	108		108
Total Impaired Loans, Recorded Investment	1,008		1,008		969
Total Impaired Loans, Unpaid Principal Balance	1,008		1,008		969
Impaired loans, additional information
Financing Receivable, Allowance for Credit Losses, Write-downs		103	14	103
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	946	884	948	734
Interest income recognized on an accrual basis on impaired loans	5	5	10	10
Interest income recognized on a cash basis on impaired loans		5	2	8
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	29	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	7		7		2
Impaired Loans with Specific Allowance, Related Allowance	7		7		2
Impaired Loans with No Specific Allowance, Recorded Investment	4		4
Total Impaired Loans, Recorded Investment	11		11		2
Total Impaired Loans, Unpaid Principal Balance	1		1		$ 2
Impaired loans, additional information
Financing Receivable, Allowance for Credit Losses, Write-downs		1		8
Average recorded investment in impaired loans and related interest income recognized
Average investment in impaired loans	$ 1	$ 15	$ 2	30
Interest income recognized on an accrual basis on impaired loans				1
Interest income recognized on a cash basis on impaired loans				$ 1