Quarterly report pursuant to Section 13 or 15(d)

Loans - Additional Information (Detail)

v3.21.2
Loans - Additional Information (Detail) - USD ($)
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Accrued interest on loans $ 11,943,000   $ 11,943,000   $ 16,363,000      
PPP loans 4,858,865,000   4,858,865,000   4,880,168,000      
Loans pledged to secure advances 2,170,000,000   2,170,000,000   2,170,000,000      
Loans held for sale, at the lower of cost or fair value 17,881,000 $ 12,834,000 17,881,000 $ 12,834,000 8,568,000 $ 36,030,000 $ 17,942,000 $ 6,020,000
Gains on sale of second draw PPP loans     13,475,000 3,478,000        
Proceeds from sale of second draw PPP loans 62,469,000 $ 29,260,000 225,223,000 $ 47,472,000        
TDR loans receivable 11,300,000   $ 11,300,000   25,000,000.0      
Principal and interest due     3 months          
Loans default payment past due period     30 days          
Total recorded investment 0   $ 0   398,000      
30-59 Days Past Due                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans Modified under provision of CARES Act, current 306,000   306,000          
60-89 Days Past Due                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans Modified under provision of CARES Act, current 0   0          
90 Days or More Past Due                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans Modified under provision of CARES Act, current 94,000   94,000          
Pass/Pass-Watch                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
PPP loans 4,645,863,000   4,645,863,000   4,663,021,000      
Special Mention                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
PPP loans 130,565,000   130,565,000   76,978,000      
Classified                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
PPP loans 82,437,000   82,437,000   140,169,000      
Payment Protection Program                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans Modified under provision of CARES Act     12,000,000.0   155,600,000      
Loans Modified under provision of CARES Act, current 12,000,000.0   12,000,000.0   155.6      
Payment Protection Program | 30-59 Days Past Due                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans previously modified under provision of CARES Act     4,400,000   4,900,000      
Payment Protection Program | 60-89 Days Past Due                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans previously modified under provision of CARES Act     900,000   1,700,000      
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     2,200,000   13,900,000      
Payment Protection Program | Pass/Pass-Watch                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans Modified under provision of CARES Act     2,600,000   99,900,000      
Payment Protection Program | Special Mention                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans Modified under provision of CARES Act     6,400,000   31,300,000      
Payment Protection Program | Classified                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans Modified under provision of CARES Act     3,000,000.0   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 17,900,000   17,900,000   8,600,000      
PPP Loans                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Gains on sale of second draw PPP loans 339,000   3,000,000.0          
Proceeds from sale of second draw PPP loans 14,600,000   132,700,000          
Accrued Interest | Payment Protection Program                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
PPP loans 21,900,000   21,900,000   295,700,000      
Modified Loans | Payment Protection Program                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Loans Modified under provision of CARES Act     12,000,000.0   155,600,000      
Loans | Accrued Interest                
Accounts, Notes, Loans and Financing Receivable [Line Items]                
Accrued interest on loans 10,200,000   10,200,000   15,200,000      
Unpaid deferred interest receivable related to loans modified under CARES Act 3,600,000   3,600,000   7,500,000      
Unpaid deferred interest receivable related to loans modified under CARES Act, net of valuation allowance $ 311,000   $ 311,000   $ 1,700,000