Loans Receivable and Allowance for Loan Losses - Analysis of Loans Modified in Troubled Debt Restructuring by Type of Concession (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	$ 1,080	$ 1,238
Extended under forbearance
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	460	0
Multiple extensions resulting from financial difficulty
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	0	0
Interest-rate reductions
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	620	1,238
TDRs in Compliance with Their Modified Terms and Accruing Interest
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	691	790
TDRs in Compliance with Their Modified Terms and Accruing Interest | Extended under forbearance
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	460	0
TDRs in Compliance with Their Modified Terms and Accruing Interest | Multiple extensions resulting from financial difficulty
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	0	0
TDRs in Compliance with Their Modified Terms and Accruing Interest | Interest-rate reductions
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	231	790
TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	389	448
TDRs in Compliance with Their Modified Terms and Not Accruing Interest | Extended under forbearance
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	0	0
TDRs in Compliance with Their Modified Terms and Not Accruing Interest | Multiple extensions resulting from financial difficulty
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	0	0
TDRs in Compliance with Their Modified Terms and Not Accruing Interest | Interest-rate reductions
Financing Receivable, Modifications [Line Items]
Amount of loans and leases modified in troubled debt restructurings	$ 389	$ 448