Quarterly report pursuant to Section 13 or 15(d)

Loans - Additional Information (Detail)

v3.21.1
Loans - Additional Information (Detail) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Accrued interest on loans $ 14,806,000   $ 16,363,000  
PPP loans included in commercial and industrial loans 4,817,151,000   4,880,168,000  
Loans pledged to secure advances 2,340,000,000   2,170,000,000  
Loans held for sale, at the lower of cost or fair value 32,674,000   8,568,000 $ 6,020,000
Gains on sale of second draw PPP loans 4,125,000 $ 1,154,000    
Proceeds from sale of second draw PPP loans 122,564,000 $ 18,212,000    
Loans 90 days or more past due and still accruing 0   0  
TDR loans receivable $ 23,600,000   25,000,000.0  
Principal and interest due 3 months      
Reserves relating to loans included in allowance for credit losses $ 7,000   16,000,000,000  
Loans default payment past due period 30 days      
Total recorded investment $ 0   398,000  
Allowance for credit losses resulting from defaulted loans     3,000  
60-89 Days Past Due        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Financing receivable, past due less than 90 days 31,800,000   53,400,000  
Pass/Pass-Watch        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
PPP loans included in commercial and industrial loans 4,573,667,000   4,663,021,000  
Special Mention        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
PPP loans included in commercial and industrial loans 96,057,000   76,978,000  
Classified        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
PPP loans included in commercial and industrial loans 147,427,000   140,169,000  
Payment Protection Program        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans Modified under provision of CARES Act 116,400,000   155,600,000  
Loans Modified under provision of CARES Act, current 116,400,000   155,600,000  
Payment Protection Program | 60-89 Days Past Due        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans previously modified under provision of CARES Act 1,700,000   1,700,000  
Payment Protection Program | 30-59 Days Past Due        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans previously modified under provision of CARES Act 5,200,000   4,900,000  
Payment Protection Program | 90 Days or More Past Due        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans previously modified under provision of CARES Act 8,000,000.0   13,900,000  
Payment Protection Program | Pass/Pass-Watch        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans Modified under provision of CARES Act 47,400,000   99,900,000  
Payment Protection Program | Special Mention        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans Modified under provision of CARES Act 50,800,000   31,300,000  
Payment Protection Program | Classified        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans Modified under provision of CARES Act 18,200,000   24,400,000  
SBA Loans        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans held for sale, at the lower of cost or fair value 10,900,000      
PPP Loans        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans held for sale, at the lower of cost or fair value 21,700,000      
Gains on sale of second draw PPP loans 2,500,000      
Proceeds from sale of second draw PPP loans 108,500,000      
Accrued Interest | Payment Protection Program        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
PPP loans included in commercial and industrial loans 256,500,000      
Modified Loans | Payment Protection Program        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans Modified under provision of CARES Act 116,400,000      
Loans | Accrued Interest        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Accrued interest on loans 13,600,000   15,200,000  
Unpaid deferred interest receivable related to loans modified under CARES Act 5,200,000   7,500,000  
Unpaid deferred interest receivable related to loans modified under CARES Act, net of valuation allowance $ 1,200,000   $ 1,700,000