Loans Receivable and Allowance for Loan Losses - Analysis of Loans Modified in Troubled Debt Restructuring by Type of Concession (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring	$ 888	$ 249	$ 5,930	$ 966
Extended under forbearance
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring		81	183	448
Interest-rate reductions
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring	705	168	5,747	518
TDRs in Compliance with Their Modified Terms and Accruing Interest
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring	437	81	3,189	495
TDRs in Compliance with Their Modified Terms and Accruing Interest | Extended under forbearance
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring		81	0	448
TDRs in Compliance with Their Modified Terms and Accruing Interest | Interest-rate reductions
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring	437	0	3,189	47
TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring	451	168	2,741	471
TDRs in Compliance with Their Modified Terms and Not Accruing Interest | Extended under forbearance
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring		0	183	0
TDRs in Compliance with Their Modified Terms and Not Accruing Interest | Interest-rate reductions
Financing Receivable, Modifications [Line Items]
Amount of loans modified in troubled debt restructuring	$ 268	$ 168	$ 2,558	$ 471