Loans (Non-Accrual Loans, Segregated by Class of Loans) (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 60,907	$ 37,833
Financing Receivable, Nonaccrual, No Allowance	22,932	18,571
Commercial Portfolio Segment [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	19,545	18,130
Financing Receivable, Nonaccrual, No Allowance	5,391	8,514
Commercial and Industrial Total Energy Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	11,500	15,224
Financing Receivable, Nonaccrual, No Allowance	7,398	7,139
Commercial Real Estate, Buildings, Land and Other [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	22,420	3,552
Financing Receivable, Nonaccrual, No Allowance	4,983	1,991
Construction Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	0
Financing Receivable, Nonaccrual, No Allowance	0	0
Total consumer real estate loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	7,442	927
Financing Receivable, Nonaccrual, No Allowance	5,160	927
Consumer Loan [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	0
Financing Receivable, Nonaccrual, No Allowance	$ 0	$ 0