Loans - Schedule of Allowances for Loan Losses by Portfolio Segment (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]    
Beginning balance $ 5,085 $ 4,580
Provision for possible loan losses 185 210
Charge-offs (217) (16)
Recoveries 12 30
Net charge-offs (205) 14
Ending balance 5,065 4,804
Commercial [Member]
   
Financing Receivable, Allowance for Credit Losses [Line Items]    
Beginning balance 1,219 933
Provision for possible loan losses (72) 242
Charge-offs (8) (6)
Recoveries 2 7
Net charge-offs (6) 1
Ending balance 1,141 1,176
Commercial Real Estate [Member]
   
Financing Receivable, Allowance for Credit Losses [Line Items]    
Beginning balance 1,872 1,902
Provision for possible loan losses 517 (78)
Charge-offs (197)   
Recoveries      
Net charge-offs (197)   
Ending balance 2,192 1,824
Residential Real Estate [Member]
   
Financing Receivable, Allowance for Credit Losses [Line Items]    
Beginning balance 1,205 1,096
Provision for possible loan losses (151) 177
Charge-offs (4)   
Recoveries 4 9
Net charge-offs    9
Ending balance 1,054 1,282
Construction & Land Development [Member]
   
Financing Receivable, Allowance for Credit Losses [Line Items]    
Beginning balance 178 253
Provision for possible loan losses (33) (119)
Charge-offs      
Recoveries      
Net charge-offs      
Ending balance 145 134
Consumer [Member]
   
Financing Receivable, Allowance for Credit Losses [Line Items]    
Beginning balance 91 76
Provision for possible loan losses (12) (12)
Charge-offs (8) (10)
Recoveries 6 14
Net charge-offs (2) 4
Ending balance 77 68
Unallocated [Member]
   
Financing Receivable, Allowance for Credit Losses [Line Items]    
Beginning balance 520 320
Provision for possible loan losses (64)   
Charge-offs      
Recoveries      
Net charge-offs      
Ending balance $ 456 $ 320