Loans - Activity in the Allowance for Credit Losses on Loans by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance			$ 245,996
Ending balance	$ 256,307		256,307
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	75,596	$ 78,465	74,006	$ 104,237
Credit loss, expense (reversal)	6,936	2,404	8,928	(18,280)
Charge-offs	(4,282)	(7,136)	(6,426)	(13,316)
Recoveries	304	1,433	2,046	2,525
Net charge-offs	(3,978)	(5,703)	(4,380)	(10,791)
Ending balance	78,554	75,166	78,554	75,166
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	14,218	19,191	17,814	18,062
Credit loss, expense (reversal)	(3,038)	(4,433)	(6,814)	(3,467)
Charge-offs	(79)	(518)	(79)	(518)
Recoveries	384	689	564	852
Net charge-offs	305	171	485	334
Ending balance	11,485	14,929	11,485	14,929
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	138,224	115,693	130,598	90,301
Credit loss, expense (reversal)	1,903	5,133	9,513	30,494
Charge-offs	(122)	0	(122)	0
Recoveries	15	100	31	131
Net charge-offs	(107)	100	(91)	131
Ending balance	140,020	120,926	140,020	120,926
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	13,857	9,708	13,538	8,004
Credit loss, expense (reversal)	2,175	3,822	3,981	5,105
Charge-offs	(408)	(1,080)	(2,077)	(1,330)
Recoveries	83	585	265	1,256
Net charge-offs	(325)	(495)	(1,812)	(74)
Ending balance	15,707	13,035	15,707	13,035
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	8,402	8,457	10,040	7,017
Credit loss, expense (reversal)	7,760	5,007	11,778	10,756
Charge-offs	(8,360)	(7,016)	(16,617)	(13,958)
Recoveries	2,739	3,115	5,340	5,748
Net charge-offs	(5,621)	(3,901)	(11,277)	(8,210)
Ending balance	10,541	9,563	10,541	9,563
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	250,297	231,514	245,996	227,621
Credit loss, expense (reversal)	15,736	11,933	27,386	24,608
Charge-offs	(13,251)	(15,750)	(25,321)	(29,122)
Recoveries	3,525	5,922	8,246	10,512
Net charge-offs	(9,726)	(9,828)	(17,075)	(18,610)
Ending balance	$ 256,307	$ 233,619	$ 256,307	$ 233,619