v3.26.1
Loans and Allowance for Credit Losses - Additional Information (Detail) - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Non Accrual Status Of Loans After Number Of Days Past Due 90 days    
Default Status Of TDRs After Number Of Days Past Due 90 days    
Charge-offs $ 9,437,000 $ 8,010,000 $ 38,366,000
Unfunded commitments related to nonperforming loans 3,800,000   200,000
Off balance sheet reserve to nonperforming loans 0   0
Total gains or losses included in earnings $ 0 0  
Forecasted Value, National Unemployment, Percent 4.51%    
Financing Receivable, before Allowance for Credit Loss $ 9,433,825,000   9,508,039,000
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery 8,200,000 3,100,000  
Post- Modification Outstanding Recorded Investment 12,840,000 3,782,000  
Small Business Administration Guarantee      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 28,100,000   31,500,000
Net Deferred Fees      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Unearned Deferred (Fees) Costs on Loans 22,700,000   21,200,000
Unearned Premiums and Discounts      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Unearned Deferred (Fees) Costs on Loans (19,100,000)   (20,200,000)
Financial Asset, 30 to 59 Days Past Due [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 26,418,000   22,032,000
Financial Asset, Not Past Due      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 9,293,858,000   9,379,203,000
Non Accrual Loans [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss $ 91,164,000   91,756,000
Weighted average [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Forecasted Value, National Unemployment, Percent 5.12%    
Maximum [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Forecasted Value, National Unemployment, Percent 5.37%    
Time and Demand Loans      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs $ 1,917,000   16,182,000
Financing Receivable, before Allowance for Credit Loss 1,196,447,000   1,226,054,000
Multifamily      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs 0   766,000
Financing Receivable, before Allowance for Credit Loss 606,179,000   594,790,000
Nonowner Occupied Commercial Real Estate      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs 2,016,000   4,770,000
Financing Receivable, before Allowance for Credit Loss 1,776,985,000   1,834,016,000
Commercial, financial, agricultural and other [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs 4,014,000 4,019,000  
Financing Receivable, before Allowance for Credit Loss 2,061,894,000   2,044,989,000
Commercial, financial, agricultural and other [Member] | Financial Asset, 30 to 59 Days Past Due [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 8,550,000   5,127,000
Commercial, financial, agricultural and other [Member] | Financial Asset, Not Past Due      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 1,997,254,000   1,992,432,000
Commercial, financial, agricultural and other [Member] | Non Accrual Loans [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 45,160,000   46,618,000
Commercial, financial, agricultural and other [Member] | Time and Demand Loans      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs 1,917,000 2,976,000  
Financing Receivable, before Allowance for Credit Loss 1,196,447,000   1,226,054,000
Commercial, financial, agricultural and other [Member] | Time and Demand Loans | Financial Asset, 30 to 59 Days Past Due [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 5,762,000   2,666,000
Commercial, financial, agricultural and other [Member] | Time and Demand Loans | Financial Asset, Not Past Due      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 1,138,449,000   1,177,868,000
Commercial, financial, agricultural and other [Member] | Time and Demand Loans | Non Accrual Loans [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 43,190,000   45,288,000
Commercial Real Estate [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs 2,308,000 1,464,000  
Financing Receivable, before Allowance for Credit Loss 3,148,767,000   3,182,109,000
Post- Modification Outstanding Recorded Investment 12,840,000 3,201,000  
Commercial Real Estate [Member] | Financial Asset, 30 to 59 Days Past Due [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 3,589,000   1,975,000
Commercial Real Estate [Member] | Financial Asset, Not Past Due      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 3,110,466,000   3,139,452,000
Commercial Real Estate [Member] | Non Accrual Loans [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 32,764,000   30,612,000
Commercial Real Estate [Member] | Multifamily      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs 0 0  
Financing Receivable, before Allowance for Credit Loss 606,179,000   594,790,000
Commercial Real Estate [Member] | Multifamily | Financial Asset, 30 to 59 Days Past Due [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 0   417,000
Commercial Real Estate [Member] | Multifamily | Financial Asset, Not Past Due      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 594,470,000   594,363,000
Commercial Real Estate [Member] | Multifamily | Non Accrual Loans [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 11,709,000   10,000
Commercial Real Estate [Member] | Nonowner Occupied Commercial Real Estate      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs 2,016,000 874,000  
Financing Receivable, before Allowance for Credit Loss 1,776,985,000   1,834,016,000
Post- Modification Outstanding Recorded Investment 12,840,000 3,201,000  
Commercial Real Estate [Member] | Nonowner Occupied Commercial Real Estate | Financial Asset, 30 to 59 Days Past Due [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 2,535,000   534,000
Commercial Real Estate [Member] | Nonowner Occupied Commercial Real Estate | Financial Asset, Not Past Due      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 1,763,714,000   1,809,256,000
Commercial Real Estate [Member] | Nonowner Occupied Commercial Real Estate | Non Accrual Loans [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 9,288,000   14,156,000
Loans to individuals [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Charge-offs 2,644,000 2,419,000  
Financing Receivable, before Allowance for Credit Loss 1,435,326,000   1,457,870,000
Loans to individuals [Member] | Financial Asset, 30 to 59 Days Past Due [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 4,285,000   6,733,000
Loans to individuals [Member] | Financial Asset, Not Past Due      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss 1,429,288,000   1,449,390,000
Loans to individuals [Member] | Non Accrual Loans [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Financing Receivable, before Allowance for Credit Loss $ 9,000   32,000
Loans to individuals [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Non Accrual Status Of Loans After Number Of Days Past Due 150 days    
Nonaccrual Commercial Loans [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans Held for sale, Amount $ 1,100,000   $ 0
Loans and Leases Receivable, Gain (Loss) on Sales, Net $ 0 $ 0