Loans and Leases Receivable and Allowance for Loan and Lease Losses - Analysis of Loans Modified in Troubled Debt Restructuring by Type of Concession (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Loan	Dec. 31, 2018 USD ($) Loan	Dec. 31, 2017 USD ($) Loan
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans | Loan	28	41	40
Recorded investment | $	$ 1,437	$ 1,675	$ 8,071
Extensions of maturity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans | Loan	2	2	5
Recorded investment | $	$ 514	$ 60	$ 6,497
Interest-rate reductions
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans | Loan	26	39	35
Recorded investment | $	$ 923	$ 1,615	$ 1,574