v3.25.2
Loans - Loans (Detail) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts $ 21,254,495 $ 20,754,813
Commercial Portfolio Segment [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 6,069,215 6,109,532
Energy Production [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 1,020,281 903,654
Energy Service [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 239,901 203,629
Energy Other [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 55,045 21,612
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
Commercial mortgage [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 7,472,048 7,165,220
Construction Loans [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 2,075,700 2,264,076
Commercial land loan [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 546,001 539,227
Commercial Real Estate Portfolio Segment [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 10,093,749 9,968,523
Home Equity Line of Credit [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 984,169 911,239
Home Equity Loan [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 972,366 914,738
Home Improvement Loans [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 872,176 852,536
Residential Mortgage [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 354,762 259,456
Other consumer real estate loans [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 155,802 165,420
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
Real Estate Loan [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts 13,433,024 13,071,912
Consumer Loan [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans, net of unearned discounts $ 437,029 $ 444,474