Loans - Additional Information (Detail) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($) SecurityLoan	Sep. 30, 2015 USD ($) SecurityLoan	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 5,487	$ 5,487	$ 8,100	$ 6,289
Ratio of the allowance for loan losses to total loans		0.97%	1.51%	1.15%
Past due 90 days still accruing	$ 1,486	$ 1,486
Company's annualized net charge off (net recovery) ratios		0.37%	(0.05%)	0.02%
Ratios of allowance for loan losses to non-accrual loans	76.70%	76.70%	728.10%	198.08%
Annual reviews of loan to ascertain the borrowers continued ability to service		$ 1,000
Loans past due period for classify to risk grade		90 days
Loans past due period for classify to substandard grade		12 months
Total impaired loans Recorded Investment	$ 23,483	$ 23,483	$ 38,400	$ 37,367
Reserve on impaired loans	$ 545	545	$ 2,900	1,514
Number of additional TDRs | SecurityLoan	2
Land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due 90 days still accruing	$ 1,486	$ 1,486
Number of loan | SecurityLoan		1
Reserve on impaired loans	266	$ 266		$ 663
Land [Member] | Real Estate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due 90 days still accruing	$ 1,500	$ 1,500