Loans - Non-Accrual Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 67,175	$ 37,833
Non-accrual with no credit loss allowance	18,693	18,571
Commercial Portfolio Segment [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	27,326	18,130
Non-accrual with no credit loss allowance	3,693	8,514
Commercial and Industrial Total Energy Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	14,200	15,224
Non-accrual with no credit loss allowance	9,698	7,139
Commercial Real Estate Buildings Land And Other Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	23,112	3,552
Non-accrual with no credit loss allowance	5,100	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	2,537	927
Non-accrual with no credit loss allowance	202	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