Loans and Allowance for Credit Losses - Summary of Amortized Cost of Nonaccrual Loans with No Related Allowance (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	$ 87,823	$ 56,347
Amortized Cost of Nonaccrual Loans with no related Allowance	42,122
Commercial and Industrial Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	33,769
Amortized Cost of Nonaccrual Loans with no related Allowance	9,916
Specialty Lending Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	19,437
Amortized Cost of Nonaccrual Loans with no related Allowance	242
Commercial Real Estate Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	28,386
Amortized Cost of Nonaccrual Loans with no related Allowance	25,733
Consumer Real Estate Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	5,345
Amortized Cost of Nonaccrual Loans with no related Allowance	5,345
Consumer Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	88
Amortized Cost of Nonaccrual Loans with no related Allowance	88
Credit Cards Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	798
Amortized Cost of Nonaccrual Loans with no related Allowance	$ 798