v3.25.2
Loans - Age Analysis of Past Due Loans, Segregated by Class of Loans (Detail) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts $ 21,254,495 $ 20,754,813
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing 48,937  
Commercial Portfolio Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 6,069,215 6,109,532
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing 7,542  
Commercial and Industrial Total Energy Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 1,315,227 1,128,895
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing 0  
Commercial Real Estate Buildings Land And Other Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 8,018,049 7,704,447
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing 36,439  
Construction Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 2,075,700 2,264,076
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing 0  
Total consumer real estate loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 3,339,275 3,103,389
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing 4,387  
Consumer Loan [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 437,029 $ 444,474
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing 569  
Financing Receivables, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 62,310  
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 26,553  
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial and Industrial Total Energy Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 1,104  
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 10,791  
Financing Receivables, 30 to 89 Days Past Due [Member] | Construction Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 0  
Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 19,316  
Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 4,546  
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 86,779  
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 27,532  
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial and Industrial Total Energy Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 4,020  
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 44,129  
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 0  
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 10,336  
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 762  
Financial Asset, Past Due    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 149,089  
Financial Asset, Past Due | Commercial Portfolio Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 54,085  
Financial Asset, Past Due | Commercial and Industrial Total Energy Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 5,124  
Financial Asset, Past Due | Commercial Real Estate Buildings Land And Other Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 54,920  
Financial Asset, Past Due | Construction Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 0  
Financial Asset, Past Due | Total consumer real estate loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 29,652  
Financial Asset, Past Due | Consumer Loan [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 5,308  
Financial Asset, Not Past Due    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 21,105,406  
Financial Asset, Not Past Due | Commercial Portfolio Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 6,015,130  
Financial Asset, Not Past Due | Commercial and Industrial Total Energy Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 1,310,103  
Financial Asset, Not Past Due | Commercial Real Estate Buildings Land And Other Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 7,963,129  
Financial Asset, Not Past Due | Construction Loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 2,075,700  
Financial Asset, Not Past Due | Total consumer real estate loans [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts 3,309,623  
Financial Asset, Not Past Due | Consumer Loan [Member]    
Financing Receivable, Past Due [Line Items]    
Loans, net of unearned discounts $ 431,721