Loans (Non-Accrual Loans, Segregated by Class of Loans) (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 37,833	$ 53,713
Financing Receivable, Nonaccrual, No Allowance	18,571	27,202
Commercial Portfolio Segment [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	18,130	22,582
Financing Receivable, Nonaccrual, No Allowance	8,514	4,701
Commercial and Industrial Total Energy Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	15,224	14,433
Financing Receivable, Nonaccrual, No Allowance	7,139	8,533
Commercial Real Estate, Buildings, Land and Other [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	3,552	15,297
Financing Receivable, Nonaccrual, No Allowance	1,991	13,817
Construction Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	948
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	927	440
Financing Receivable, Nonaccrual, No Allowance	927	138
Consumer Loan [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	13
Financing Receivable, Nonaccrual, No Allowance	$ 0	$ 13