Loans and Allowance for Credit Losses - Recorded Investment and Unpaid Principal Balance for Impaired Loans with Associated Allowance (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	$ 18,885		$ 27,267
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	33,851		48,543
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	20,628	$ 30,168
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	(42)	(20)
Impaired Financing Receivable, with Related Allowance, Recorded Investment	23,561		12,205
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	25,709		13,778
Related allowance	5,374		4,549
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	16,259	8,980
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Recorded investment	42,446		39,472
Unpaid principal balance	59,560		62,321
Impaired Financing Receivable, Average Recorded Investment	36,887	39,148
Impaired Financing Receivable, Interest Income, Cash Basis Method	(42)	(20)
Commercial, financial, agricultural and other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,314		4,369
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	16,606		18,014
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	3,499	1,693
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,443		5,691
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	7,467		6,787
Related allowance	3,252		4,044
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	5,200	7,445
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Construction
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,288		3,288
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,288		3,288
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		0
Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	7,488		7,042
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	9,231		8,763
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	7,436	6,069
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	(7)	(20)
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,531		1,531
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,697		1,697
Related allowance	166		118
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,531	824
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	4,649		12,402
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	4,538		18,219
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	6,252	21,974
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	(34)	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	15,587		4,983
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	16,545		5,294
Related allowance	1,956		387
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	9,528	711
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Loans to individuals [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	146		166
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	188		259
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	153	432
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	(1)	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Real estate construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	3,288	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Time and Demand Loans | Commercial, financial, agricultural and other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,580		3,527
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	15,872		17,172
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,731	1,455
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,443		5,691
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	7,467		6,787
Related allowance	3,252		4,044
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	5,200	7,445
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Senior Lien | Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	4,296		4,161
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	5,309		5,151
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	4,279	3,437
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	(7)	(20)
Impaired Financing Receivable, with Related Allowance, Recorded Investment	283		282
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	279		279
Related allowance	61		39
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	282	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Junior Lien | Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,192		2,881
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,922		3,612
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	3,157	2,632
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,248		1,249
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,418		1,418
Related allowance	105		79
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,249	824
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Multifamily | Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	51		55
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	55		58
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	52	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Nonowner Occupied Commercial Real Estate | Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,080		10,971
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,296		17,092
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	4,061	20,487
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	(1)	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	13,051		3,311
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	13,862		3,550
Related allowance	1,537		174
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	7,734	115
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Owner Occupied Commercial Real Estate | Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,518		1,376
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,187		1,069
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,139	1,487
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	(33)	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,536		1,672
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2,683		1,744
Related allowance	419		213
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,794	596
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Automobiles | Loans to individuals [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	144		164
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	185		257
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	151	356
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	(1)	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Other Consumer Loans | Loans to individuals [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2		2
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3		2
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2	76
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Construction Residential | Construction
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0		0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		0
Construction Residential | Real estate construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Construction Other | Construction
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,288		3,288
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,288		3,288
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		0
Construction Other | Real estate construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	3,288	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Time and Demand Loans Other | Commercial, financial, agricultural and other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0		0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0
Equipment Finance | Commercial, financial, agricultural and other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	734		842
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	734		842
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	768	238
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Related allowance	0		$ 0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	$ 0	$ 0