Loans and Leases - Allowance for Credit Losses, Loans and Leases Roll Forward (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 85,387	$ 79,004	$ 71,924
Provision (reversal of provision) for credit losses	5,506	11,780	10,975
Charge-offs	(5,033)	(6,186)	(4,669)
Recoveries	1,231	789	774
Ending balance	87,091	85,387	79,004
Commercial, Financial and Agricultural [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	13,699	16,920	13,538
Provision (reversal of provision) for credit losses	4,709	1,289	3,705
Charge-offs	(2,926)	(4,877)	(887)
Recoveries	597	367	564
Ending balance	16,079	13,699	16,920
Real Estate-Commercial [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	45,849	41,673	41,095
Provision (reversal of provision) for credit losses	1,039	4,213	3,854
Charge-offs	(35)	(50)	(3,282)
Recoveries	14	13	6
Ending balance	46,867	45,849	41,673
Real Estate-Construction [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,543	4,952	4,575
Provision (reversal of provision) for credit losses	(1,119)	1,797	377
Charge-offs	(500)	(207)	0
Recoveries	0	1	0
Ending balance	4,924	6,543	4,952
Real Estate-Residential Secured for Business Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	8,692	7,054	6,482
Provision (reversal of provision) for credit losses	(1,436)	1,503	517
Charge-offs	0	(50)	0
Recoveries	235	185	55
Ending balance	7,491	8,692	7,054
Real Estate-Residential Secured for Personal Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,349	3,685	2,403
Provision (reversal of provision) for credit losses	739	2,664	1,282
Charge-offs	0	0	0
Recoveries	134	0	0
Ending balance	7,222	6,349	3,685
Real Estate-Home Equity Secured for Personal Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,289	1,287	1,028
Provision (reversal of provision) for credit losses	371	4	221
Charge-offs	0	(85)	0
Recoveries	46	83	38
Ending balance	1,706	1,289	1,287
Loans to Individuals [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	392	351	363
Provision (reversal of provision) for credit losses	778	467	167
Charge-offs	(921)	(507)	(255)
Recoveries	93	81	76
Ending balance	342	392	351
Lease Financings [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,574	3,082	2,290
Provision (reversal of provision) for credit losses	425	(157)	1,002
Charge-offs	(651)	(410)	(245)
Recoveries	112	59	35
Ending balance	$ 2,460	2,574	3,082
Unallocated [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance		$ 0	150
Provision (reversal of provision) for credit losses			(150)
Ending balance			$ 0