Non-performing Loans and Impaired Loans - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014 Contract ConsecutivePayment	Dec. 31, 2013
Financing Receivable, Modifications [Line Items]
Non-accrual loans	$ 9,844,000	$ 9,748,000
Non-performing TDR's	3,200,000
Loans acquired included in non-accrual loans	1,200,000
Loans acquired included in non-performing TDR's	482,000
Loan delinquency period	90 days
Minimum period required for satisfactory performance to return loan from non-accrual to accrual status	6 months
Restructured loans with modified recorded balances	0
Restructured loan returned to accruing status number of Consecutive Payments of loan	6
Restructured loan reported in TDRs	8,800,000
Specific reserves allocated to troubled debt restructuring	1,500,000
Number TDR's returned to accrual status	0
Loans classified as TDR after a period	90 days
Good Pass [Member]
Financing Receivable, Modifications [Line Items]
Number of consecutive years of profit Unaudited Financial Information for Good Pass Rating	5 years
Number of years of Satisfactory Relationship with bank for Good Pass Rating	5 years
Performing Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Restructured loan	5,600,000
Minimum [Member]
Financing Receivable, Modifications [Line Items]
Delay or shortfall in payments of loan	30 days
Period for loans moved to non-accrual status	90 days
Loans with an aggregate credit exposure	1,000,000
Minimum [Member] | Good Pass [Member]
Financing Receivable, Modifications [Line Items]
Number of consecutive years of profit for Good Pass Rating	3 years
Minimum [Member] | Satisfactory Pass [Member]
Financing Receivable, Modifications [Line Items]
Minimum number of years of Satisfactory Repayment required for Satisfactory Pass Rating	2 years
Maximum [Member]
Financing Receivable, Modifications [Line Items]
Loans with an aggregate credit exposure	$ 2,500,000