Loans, Leases and Allowance for Credit Losses - Interest Income on Impaired Loans by Loan Class (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	$ 4,794	$ 5,494	$ 6,235
Owner occupied [Member] | Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	1,575	1,550	1,726
Non-owner occupied [Member] | Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	1,560	1,484	2,043
Multi-family [Member] | Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	0	1	0
Commercial [Member] | Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	288	745	1,087
Leases [Member] | Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	0	0	0
Construction [Member] | Construction and land development [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	0	0	0
Land [Member] | Construction and land development [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	785	1,021	1,288
Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	579	646	62
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	$ 7	$ 47	$ 29