Loans and Leases - Allowance for Loan and Lease Losses and Recorded Investment in Loans and Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	$ 1,945	$ 1,787
Ending balance: pooled	85,146	83,600
Total: Allowance for Credit Loss	87,091	85,387	$ 79,004	$ 71,924
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	12,056	20,747
Ending balance: pooled	6,814,527	6,546,467
Total ending balance	6,826,583	6,567,214
Commercial, Financial and Agricultural [Member]
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	1,922	692
Ending balance: pooled	14,157	13,007
Total: Allowance for Credit Loss	16,079	13,699	16,920	13,538
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	3,795	2,551
Ending balance: pooled	1,034,040	987,172
Total ending balance	1,037,835	989,723
Real Estate-Commercial [Member]
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	23	20
Ending balance: pooled	46,844	45,829
Total: Allowance for Credit Loss	46,867	45,849	41,673	41,095
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	2,679	5,709
Ending balance: pooled	3,527,772	3,297,089
Total ending balance	3,530,451	3,302,798
Real Estate-Construction [Member]
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	0	1,075
Ending balance: pooled	4,924	5,468
Total: Allowance for Credit Loss	4,924	6,543	4,952	4,575
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	0	6,067
Ending balance: pooled	274,483	388,395
Total ending balance	274,483	394,462
Real Estate-Residential Secured for Business Purpose [Member]
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	0	0
Ending balance: pooled	7,491	8,692
Total: Allowance for Credit Loss	7,491	8,692	7,054	6,482
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	586	1,090
Ending balance: pooled	535,509	515,912
Total ending balance	536,095	517,002
Real Estate-Residential Secured for Personal Purpose [Member]
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	0	0
Ending balance: pooled	7,222	6,349
Total: Allowance for Credit Loss	7,222	6,349	3,685	2,403
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	3,805	4,214
Ending balance: pooled	991,167	904,801
Total ending balance	994,972	909,015
Real Estate-Home Equity Secured for Personal Purpose [Member]
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	0	0
Ending balance: pooled	1,706	1,289
Total: Allowance for Credit Loss	1,706	1,289	1,287	1,028
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	1,191	1,116
Ending balance: pooled	185,645	178,166
Total ending balance	186,836	179,282
Loans to Individuals [Member]
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	0	0
Ending balance: pooled	342	392
Total: Allowance for Credit Loss	342	392	351	363
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	0	0
Ending balance: pooled	21,250	27,749
Total ending balance	21,250	27,749
Lease Financings [Member]
Allowance For Credit Losses, Loans And Leases [Abstract]
Ending balance: individually analyzed	0	0
Ending balance: pooled	2,460	2,574
Total: Allowance for Credit Loss	2,460	2,574	$ 3,082	$ 2,290
Loans and Leases Held for Investment [Abstract]
Ending balance: individually analyzed	0	0
Ending balance: pooled	244,661	247,183
Total ending balance	$ 244,661	$ 247,183