Loans - Non-Accrual Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 38,410	$ 37,833
Non-accrual with no credit loss allowance	24,550	18,571
Commercial Portfolio Segment [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	10,494	18,130
Non-accrual with no credit loss allowance	4,962	8,514
Commercial and Industrial Total Energy Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	22,349	15,224
Non-accrual with no credit loss allowance	14,515	7,139
Commercial Real Estate Buildings Land And Other Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	4,604	3,552
Non-accrual with no credit loss allowance	4,110	1,991
Construction Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	0
Non-accrual with no credit loss allowance	0	0
Total consumer real estate loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	963	927
Non-accrual with no credit loss allowance	963	927
Consumer Loan [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	0
Non-accrual with no credit loss allowance	$ 0	$ 0