Allocation of Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	$ 6,419	$ 5,928	$ 6,095
Allowance for loan losses, percentage of total	100.00%		100.00%
Commercial Non Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	$ 830		$ 713
Allowance for loan losses, percentage of total	15.70%		15.30%
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	$ 2,788		$ 3,355
Allowance for loan losses, percentage of total	58.10%		57.90%
Consumer Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	$ 1,512		$ 1,852
Allowance for loan losses, percentage of total	23.40%		24.20%
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	$ 148		$ 175
Allowance for loan losses, percentage of total	2.70%		2.60%
Unallocated
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	$ 1,141		$ 0
Allowance for loan losses, percentage of total	0.10%		0.00%