Loans and Allowance for Loan and Lease Losses - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) SecurityLoan	Jun. 30, 2014 SecurityLoan	Jun. 30, 2015 USD ($) SecurityLoan Methodologies RiskGrades	Jun. 30, 2014 SecurityLoan	Dec. 31, 2014 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Period used to calculate required all without specific reserve			36 months
Number of methodologies | Methodologies			3
Number of years taken into account for borrower's historic cash flows for grade one			5 years
Borrower rating, grade nine doubtful | RiskGrades			9
Borrower rating, grade eight substandard | RiskGrades			8
Period of loan transferred to non-accrual			90 days
Troubled debt restructurings part of non-accrual loans	$ 1,411,000		$ 1,411,000		$ 1,082,000
Number of TDR loans | SecurityLoan		0		0
Number of days for delay in payment			90 days
Periods of restructuring loans past due			12 months
Number of troubled debt restructured loans with default payment | SecurityLoan	0	0	0	0
Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Amount of Charge-offs to be approved by Chief Credit Officer	$ 100,000		$ 100,000
Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Amount of forgiveness of debt required to be approved by Loan Committee	100,000		100,000
Amount of Charge-offs to be approved by Chief Credit Officer	$ 10,000		$ 10,000