Loans and Allowance for Loan and Lease Losses - Classes of Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 332,542		$ 321,025
Undisbursed loan proceeds	594		302
Deferred loan fees, net	622		707
Allowance for loan losses	3,904	$ 3,984	3,903	$ 4,004	$ 4,100	$ 3,993
Less: Undisbursed loan proceeds, Deferred loan fees and expenses, net Allowance for loan losses	5,120		4,912
Total loans - net	327,422		316,113
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	116,472		111,455
Allowance for loan losses	1,087	1,133	1,059	1,248	1,273	1,165
Residential Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	163,467		163,839
Allowance for loan losses	2,021	1,983	1,934	1,683	1,747	1,743
Construction Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	18,637		13,570
Allowance for loan losses	202	225	156	392	332	356
Commercial Loans and Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	30,196		29,358
Allowance for loan losses	469	512	637	558	629	623
Municipal Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,895		785
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,875		2,018
Allowance for loan losses	$ 125	$ 131	$ 117	$ 123	$ 119	$ 106