Quarterly report pursuant to Section 13 or 15(d)

Loans - Additional Information (Detail)

v3.20.2
Loans - Additional Information (Detail)
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2020
USD ($)
Loan
Sep. 30, 2020
USD ($)
Loan
Dec. 31, 2019
USD ($)
Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Accrued interest on loans $ 21,417,000 $ 21,417,000 $ 11,742,000
Loans pledged to secure advances 2,270,000,000 2,270,000,000 1,350,000,000
PPP loans included in commercial and industrial loans 4,834,137,000 4,834,137,000 4,610,147,000
Loans 90 days or more past due and still accruing 0 0 0
TDR loans receivable 25,900,000 $ 25,900,000 56,300,000
Principal and interest due   3 months  
Reserves relating to loans included in allowance for credit losses 25,000 $ 25,000 22,700,000
Loans default payment past due period   30 days  
Total recorded investment $ 398,000,000,000 $ 398,000,000,000 $ 132,000
Number of defaulted loans | Loan 0 1 1
Pass/Pass-Watch      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
PPP loans included in commercial and industrial loans $ 4,670,821,000 $ 4,670,821,000  
Special Mention      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
PPP loans included in commercial and industrial loans 57,105,000 57,105,000  
Classified      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
PPP loans included in commercial and industrial loans 106,211,000 106,211,000  
Payment Protection Program      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
PPP loans included in commercial and industrial loans 302,900,000 302,900,000  
Loans Modified under provision of CARES Act   578,500,000  
Payment Protection Program | Pass/Pass-Watch      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans Modified under provision of CARES Act   524,900,000  
Payment Protection Program | Special Mention      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans Modified under provision of CARES Act   30,100,000  
Payment Protection Program | Classified      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans Modified under provision of CARES Act   23,500,000  
Loans | Accrued Interest      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Accrued interest on loans 20,200,000 20,200,000 $ 10,000,000.0
Loans | Accrued Interest | Payment Protection Program      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Accrued interest on loans 578,500,000 578,500,000  
Loans | Modified Loans | Accrued Interest | Payment Protection Program      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Accrued interest on loans $ 8,800,000 $ 8,800,000