Loans Receivable and Allowance for Loan Losses - Summary of Loans Modified in Troubled Debt Restructurings and Related Recorded Investment (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) Loan	Sep. 30, 2014 USD ($) Loan	Sep. 30, 2015 USD ($) Loan	Sep. 30, 2014 USD ($) Loan
TDRs in Compliance with Their Modified Terms and Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings	15	2	92	10
Recorded investment | $	$ 437	$ 81	$ 3,189	$ 495
TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings	7	2	40	7
Recorded investment | $	$ 451	$ 168	$ 2,741	$ 471
Commercial and industrial (including owner occupied commercial real estate) | TDRs in Compliance with Their Modified Terms and Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings	0		0
Recorded investment | $	$ 0		$ 0
Commercial and industrial (including owner occupied commercial real estate) | TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings	1		2
Recorded investment | $	$ 183		$ 527
Commercial real estate non-owner occupied | TDRs in Compliance with Their Modified Terms and Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings			0
Recorded investment | $			$ 0
Commercial real estate non-owner occupied | TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings			1
Recorded investment | $			$ 209
Manufactured housing | TDRs in Compliance with Their Modified Terms and Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings	14	0	90	1
Recorded investment | $	$ 431	$ 0	$ 2,988	$ 47
Manufactured housing | TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings	6	2	37	7
Recorded investment | $	$ 268	$ 168	$ 2,005	$ 471
Residential real estate | TDRs in Compliance with Their Modified Terms and Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings	1		2
Recorded investment | $	$ 6		$ 201
Residential real estate | TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings	0		0
Recorded investment | $	$ 0		$ 0
Other | TDRs in Compliance with Their Modified Terms and Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings		2		9
Recorded investment | $		$ 81		$ 448
Other | TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Number of loans modified in troubled debt restructurings		0		0
Recorded investment | $		$ 0		$ 0