v3.26.1
Loans Held-for-Investment and Allowance for Credit Losses - Additional Information (Detail) - USD ($)
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
 [1]
Jun. 30, 2026
Jun. 30, 2025
 [2]
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 $ 67,038,000   $ 67,038,000   $ 56,492,000
Additional funds advanced in connection with impaired loans 0   0    
Loans held by subsidiaries subject to blanket liens 7,190,793,000   7,190,793,000    
Off-balance sheet commitments 1,890,534,000   1,890,534,000    
Provision for loan losses 3,915,000 [1] $ 2,432,000 6,653,000 [2] $ 5,423,000  
Business assets [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Collateral Dependent Commercial Loans 86,000   86,000   110,000
Real Estate [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Collateral Dependent Commercial Loans 28,285,000   28,285,000   23,867,000
Federal Home Loan Bank Borrowings [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Available line of credit 2,250,612,000   2,250,612,000    
Undisbursed commitments 668,000,000   668,000,000    
Federal Reserve Discount Window [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Available line of credit 1,628,678,000   1,628,678,000    
Undisbursed commitments 0   0    
Commitments to Extend Credit [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Reserve for unfunded commitments $ 6,208,000   $ 6,208,000   $ 6,387,000
[1] For the three-months ended June 30, 2026 and 2025, the provision for credit losses of $4,183,000 and $3,132,000, respectively, on the consolidated statements of earnings includes a provision for credit losses on loans of $3,915,000 and $2,432,000, respectively, and a provision for off-balance sheet unfunded commitments of $268,000 and $700,000, respectively.
[2] For the six-months ended June 30, 2026 and 2025, the provision for credit losses of $6,474,000 and $6,660,000, respectively, on the consolidated statements of earnings includes a provision for credit losses on loans of $6,653,000 and $5,423,000, respectively, and a provision reversal for off-balance sheet unfunded commitments of $179,000, and provision for off-balance sheet unfunded commitments of $1,237,000, respectively.