Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	$ 100,000	$ 919,000
Total past due loans 60 - 89 Days Past Due	44,000	190,000
Total past due loans Greater Than 89 Days Past Due	798,000	5,008,000
Total Past Due	942,000	6,117,000
Current	1,052,301,000	1,035,072,000
Total Loans	1,053,243,000	1,041,189,000	1,072,422,000
Recorded Balance greater than 89 Days and Accruing	0	0
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	0	80,000
Total past due loans 60 - 89 Days Past Due	0	0
Total past due loans Greater Than 89 Days Past Due	309,000	871,000
Total Past Due	309,000	951,000
Current	286,064,000	284,371,000
Total Loans	286,373,000	285,322,000
Recorded Balance greater than 89 Days and Accruing	0	0
Commercial Vacant Land, Land Development, and Residential Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	0	289,000
Total past due loans 60 - 89 Days Past Due	0	0
Total past due loans Greater Than 89 Days Past Due	0	614,000
Total Past Due	0	903,000
Current	36,741,000	47,196,000
Total Loans	36,741,000	48,099,000
Recorded Balance greater than 89 Days and Accruing	0	0
Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	65,000	199,000
Total past due loans 60 - 89 Days Past Due	0	0
Total past due loans Greater Than 89 Days Past Due	50,000	1,337,000
Total Past Due	115,000	1,536,000
Current	261,762,000	257,741,000
Total Loans	261,877,000	259,277,000
Recorded Balance greater than 89 Days and Accruing	0	0
Commercial Real Estate - Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	0	303,000
Total past due loans 60 - 89 Days Past Due	0	0
Total past due loans Greater Than 89 Days Past Due	0	1,123,000
Total Past Due	0	1,426,000
Current	364,066,000	323,460,000
Total Loans	364,066,000	324,886,000
Recorded Balance greater than 89 Days and Accruing	0	0
Commercial Real Estate - Multi-Family and Residential Rental [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	0	0
Total past due loans 60 - 89 Days Past Due	0	0
Total past due loans Greater Than 89 Days Past Due	64,000	613,000
Total Past Due	64,000	613,000
Current	37,575,000	50,309,000
Total Loans	37,639,000	50,922,000
Recorded Balance greater than 89 Days and Accruing	0	0
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	65,000	871,000
Total past due loans 60 - 89 Days Past Due	0	0
Total past due loans Greater Than 89 Days Past Due	423,000	4,558,000
Total Past Due	488,000	5,429,000
Current	986,208,000	963,077,000
Total Loans	986,696,000	968,506,000	996,905,000
Recorded Balance greater than 89 Days and Accruing	0	0
Retail Home Equity and Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	14,000	1,000
Total past due loans 60 - 89 Days Past Due	0	0
Total past due loans Greater Than 89 Days Past Due	0	13,000
Total Past Due	14,000	14,000
Current	35,066,000	38,903,000
Total Loans	35,080,000	38,917,000
Recorded Balance greater than 89 Days and Accruing	0	0
Retail 1-4 Family Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	21,000	47,000
Total past due loans 60 - 89 Days Past Due	44,000	190,000
Total past due loans Greater Than 89 Days Past Due	375,000	437,000
Total Past Due	440,000	674,000
Current	31,027,000	33,092,000
Total Loans	31,467,000	33,766,000
Recorded Balance greater than 89 Days and Accruing	0	0
Retail Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due loans 30 - 59 Days Past Due	35,000	48,000
Total past due loans 60 - 89 Days Past Due	44,000	190,000
Total past due loans Greater Than 89 Days Past Due	375,000	450,000
Total Past Due	454,000	688,000
Current	66,093,000	71,995,000
Total Loans	66,547,000	72,683,000	75,517,000
Recorded Balance greater than 89 Days and Accruing	$ 0	$ 0