v3.26.1
Loans Held-for-Investment and Allowance for Credit Losses - Additional Information (Detail) - USD ($)
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Nonaccrual, past due 90 days or more and still accruing, restructured loans and foreclosed assets $ 54,309,000   $ 56,492,000
Additional funds advanced in connection with impaired loans 0    
Loans held by subsidiaries subject to blanket liens 7,400,995,000    
Off-balance sheet commitments 1,794,686,000   537,000
Provision for loan losses [1] 2,738,000 $ 2,991,000  
Business assets [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Collateral Dependent Commercial Loans 89,000   110,000
Real Estate [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Collateral Dependent Commercial Loans 22,530,000   23,867,000
Federal Home Loan Bank Borrowings [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Available line of credit 2,313,929,000    
Undisbursed commitments 633,000,000    
Federal Reserve Discount Window [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Available line of credit 1,869,712,000    
Undisbursed commitments 0    
Commitments to Extend Credit [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Reserve for unfunded commitments $ 5,940,000   $ 6,387,000
[1] For the three-months ended March 31, 2026 and 2025, the provision for credit losses of $2,291,000 and $3,528,000, respectively, on the consolidated statements of earnings includes a provision for credit losses on loans of $2,738,000 and $2,991,000, respectively, and a reversal of provision for off-balance sheet unfunded commitments of $447,000, and provision for off-balance sheet unfunded commitments of $537,000, respectively.