Loans and Allowance for Credit Losses - Summary of Amortized Cost of Nonaccrual Loans with No Related Allowance (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	$ 76,706	$ 87,823
Amortized Cost of Nonaccrual Loans with no related Allowance	34,100	42,122
Commercial and Industrial Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	30,181	33,769
Amortized Cost of Nonaccrual Loans with no related Allowance	11,060	9,916
Specialty Lending Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	19,083	19,437
Amortized Cost of Nonaccrual Loans with no related Allowance	1,674	242
Commercial Real Estate Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	21,297	28,386
Amortized Cost of Nonaccrual Loans with no related Allowance	15,221	25,733
Consumer Real Estate Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	5,372	5,345
Amortized Cost of Nonaccrual Loans with no related Allowance	5,372	5,345
Consumer Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	73	88
Amortized Cost of Nonaccrual Loans with no related Allowance	73	88
Credit Cards Portfolio [Member]
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans	700	798
Amortized Cost of Nonaccrual Loans with no related Allowance	$ 700	$ 798