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, 2023	Mar. 31, 2022	Dec. 31, 2022
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	$ 31,345		$ 34,319
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	44,654		45,247
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	30,168	$ 37,509
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	20	130
Impaired Financing Receivable, with Related Allowance, Recorded Investment	12,889		1,168
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	16,390		1,186
Related allowance	9,762		711
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	8,980	800
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	6
Recorded investment	44,234		35,487
Unpaid principal balance	61,044		46,433
Impaired Financing Receivable, Average Recorded Investment	39,148	38,309
Impaired Financing Receivable, Interest Income, Cash Basis Method	20	136
Commercial, financial, agricultural and other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,808		3,141
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	10,187		9,555
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,693	3,561
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	29
Impaired Financing Receivable, with Related Allowance, Recorded Investment	10,556		1,168
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	13,881		1,186
Related allowance	9,071		711
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	7,445	384
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	6
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
Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	6,419		9,145
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	8,312		11,010
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	6,069	9,201
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	20	84
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,237		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,406		0
Related allowance	103		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	824	0
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	22,689		21,505
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	25,685		24,119
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	21,974	24,312
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	13
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,096		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,103		0
Related allowance	588		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	711	416
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	429		528
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	470		563
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	432	435
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	4
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	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
Time and Demand Loans | Commercial, financial, agricultural and other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,607		3,141
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	9,978		9,555
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,455	3,561
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	29
Impaired Financing Receivable, with Related Allowance, Recorded Investment	10,556		1,168
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	13,881		1,186
Related allowance	9,071		711
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	7,445	384
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	6
Senior Lien | Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,543		5,754
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	4,633		6,848
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	3,437	5,197
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	20	62
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
Junior Lien | Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,876		3,391
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,679		4,162
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,632	4,004
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	22
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,237		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,406		0
Related allowance	103		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	824	0
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	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	416
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	20,938		20,155
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	23,063		22,565
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	20,487	22,714
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	9
Impaired Financing Receivable, with Related Allowance, Recorded Investment	173		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	212		0
Related allowance	172		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	115	0
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	1,751		1,350
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,622		1,554
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,487	1,598
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	4
Impaired Financing Receivable, with Related Allowance, Recorded Investment	923		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	891		0
Related allowance	416		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	596	0
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	355		440
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	396		475
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	356	350
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0	4
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	74		88
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	74		88
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	76	85
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	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 Other | 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
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	201		0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	209		0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	238	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