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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Modifications [Line Items]
Total TDRs	$ 3,417	$ 7,273	$ 3,417	$ 7,273
Performing TDRs [Member]
Financing Receivable, Modifications [Line Items]
Beginning balance	3,219	4,530	3,594	4,809
New modifications	0	0	0	311
Payoffs/payments, net and other	(51)	(777)	(426)	(1,367)
TDRs returned to accrual status	0	0	0	0
TDRs placed on nonaccrual status	0	0	0	0
Ending balance	3,168	3,753	3,168	3,753
Nonperforming TDRs [Member]
Financing Receivable, Modifications [Line Items]
Beginning balance	263	3,892	3,509	4,200
New modifications	0	278	0	316
Charge-offs	0	0	(78)	0
Transfer to OREO	0	0	(2,275)	0
Payoffs/payments, net and other	(14)	(650)	(907)	(996)
TDRs returned to accrual status	0	0	0	0
TDRs placed on nonaccrual status	0	0	0	0
Ending balance	$ 249	$ 3,520	$ 249	$ 3,520