Loans and Lease Finance Receivables and Allowance for Credit Losses - Schedule of Recorded Investment in, and Aging of, Past Due and Nonaccrual Loans, Including PCI Loans by Class of Loans (Parenthetical) (Detail) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing loans, current	$ 2,100,000	$ 1,400,000
Nonaccrual	13,769,000	14,347,000
Nonaccrual loans		184,000
30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual		2,000
60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual	400,000	1,300,000
90+ Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual	$ 11,200,000	$ 11,600,000