Loans Receivable and Allowance for Loan Losses - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) Allowance Commitment Loan	Sep. 30, 2014 USD ($) Allowance	Sep. 30, 2015 USD ($) Allowance Commitment Loan	Sep. 30, 2014 USD ($) Allowance	Dec. 31, 2014 USD ($) Commitment
Financing Receivable, Modifications [Line Items]
FDIC Loss Sharing Arrangement, clawback liability payment date (days)			45 days
FDIC Loss Sharing Arrangement, clawback liability	$ 2,300		$ 2,300
FDIC Loss Sharing Arrangement, expected FDIC receivable	2,500		2,500
FDIC Loss Sharing Arrangement, clawback liability net of FDIC receivable	200		200
Loans reported as TDR	$ 10,500		$ 10,500		$ 5,000
Minimum performance requirement (months)			6 months
Number of commitments to lend additional funds (commitment) | Commitment	0		0		0
Recorded investment of loans determined to be TDRs	$ 900		$ 5,900
Loans modified in TDR allowance | Allowance	1	0	3	0
Funds for reimbursement	$ 1,200		$ 1,200		$ 3,000
TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Recorded investment	$ 451	$ 168	$ 2,741	$ 471
Commercial and industrial (including owner occupied commercial real estate)
Financing Receivable, Modifications [Line Items]
Loans modified in TDR allowance | Allowance	1		2
Allowance for credit losses, effect of change in method	$ 100		$ 200
Commercial and industrial (including owner occupied commercial real estate) | Troubled Debt Restructurings
Financing Receivable, Modifications [Line Items]
Number of contracts (loan) | Loan	1		2
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]
Recorded investment	$ 183		$ 527
Commercial real estate non-owner occupied | Troubled Debt Restructurings
Financing Receivable, Modifications [Line Items]
Number of contracts (loan) | Loan			1
Commercial real estate non-owner occupied | TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Recorded investment			$ 209
Manufactured housing | Troubled Debt Restructurings
Financing Receivable, Modifications [Line Items]
Number of contracts (loan) | Loan	6		37
Manufactured housing | TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Recorded investment	$ 268	$ 168	$ 2,005	$ 471
Residential real estate
Financing Receivable, Modifications [Line Items]
Loans modified in TDR allowance | Allowance			1
Allowance for credit losses, effect of change in method			$ 100
Residential real estate held in other real estate owned	2,200		2,200
Residential real estate | TDRs in Compliance with Their Modified Terms and Not Accruing Interest
Financing Receivable, Modifications [Line Items]
Recorded investment	$ 0		$ 0