Loans and Lease Finance Receivables and Allowance for Loan Losses - Summary of Activity Related to Troubled Debt Restructurings (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Financing Receivable, Modifications [Line Items]
Total TDRs	$ 30,051	$ 60,361	$ 30,051	$ 60,361
Performing TDRs [Member]
Financing Receivable, Modifications [Line Items]
Beginning balance	20,292	45,166	42,687	53,589
New modifications	759	2,353	1,877	2,383
Payoffs and payments, net	(2,584)	(2,306)	(26,097)	(11,275)
TDRs returned to accrual status	8,551	0	8,551	516
TDRs placed on nonaccrual status	0	0	0	0
Ending balance	27,018	45,213	27,018	45,213
Nonperforming TDRs [Member]
Financing Receivable, Modifications [Line Items]
Beginning balance	12,029	15,167	12,622	20,285
New modifications	20	330	102	661
Charge-offs	0	0	(38)	0
Transfer to OREO	0	0	0	(842)
Payoffs and payments, net	(465)	(349)	(1,102)	(4,440)
TDRs returned to accrual status	(8,551)	0	(8,551)	(516)
TDRs placed on nonaccrual status	0	0	0	0
Ending balance	$ 3,033	$ 15,148	$ 3,033	$ 15,148