v3.25.2
Loans - Investment in Loans Related to Allowance for Loan Losses by Portfolio Segment Disaggregated Based on Impairment Methodology (Detail) - USD ($)
$ in Thousands
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts $ 21,254,495   $ 20,754,813      
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 277,803   270,151      
Commercial Portfolio Segment [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 6,069,215   6,109,532      
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 95,484 $ 94,307 87,569 $ 78,554 $ 75,596 $ 74,006
Commercial and Industrial Total Energy Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 1,315,227   1,128,895      
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 10,389 10,256 9,992 11,485 14,218 17,814
Commercial Real Estate Buildings Land And Other Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 8,018,049   7,704,447      
Construction Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 2,075,700   2,264,076      
Total consumer real estate loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 3,339,275   3,103,389      
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 21,707 18,924 19,106 15,707 13,857 13,538
Consumer Loan [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 437,029   444,474      
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 9,300 $ 8,824 10,279 $ 10,541 $ 8,402 $ 10,040
Specific Valuation Allowances [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 19,939   17,521      
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 15,343   13,265      
Specific Valuation Allowances [Member] | Commercial and Industrial Total Energy Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 2,677   2,700      
Specific Valuation Allowances [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 1,235   122      
Specific Valuation Allowances [Member] | Construction Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 0   503      
Specific Valuation Allowances [Member] | Total consumer real estate loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 684   766      
Specific Valuation Allowances [Member] | Consumer Loan [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest 0   165      
Loans Individually Evaluated for Impairment [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 59,906   76,287      
Loans Individually Evaluated for Impairment [Member] | Commercial Portfolio Segment [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 36,745   45,009      
Loans Individually Evaluated for Impairment [Member] | Commercial and Industrial Total Energy Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 4,020   4,078      
Loans Individually Evaluated for Impairment [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 13,322   18,797      
Loans Individually Evaluated for Impairment [Member] | Construction Loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 0   2,012      
Loans Individually Evaluated for Impairment [Member] | Total consumer real estate loans [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts 5,819   6,039      
Loans Individually Evaluated for Impairment [Member] | Consumer Loan [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Loans, net of unearned discounts $ 0   $ 352