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 ($)	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing loans, current	$ 1,400,000	$ 1,200,000
Nonaccrual	14,347,000	5,277,000
Small Business Administration Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual	2,273,000	2,032,000
Small Business Administration Loans [Member] | Financial Guarantee [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	184,000	2,000,000.0
30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual	2,000	59,000
60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual	1,300,000	1,100,000
90+ Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual	$ 11,600,000	$ 2,900,000