Loans and Allowance for Credit Losses - Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 117,718	$ 102,906	$ 102,906
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		22,079
Charge-offs	(5,563)	(1,883)	(33,267)
Recoveries	1,261	710	3,115
Provision for credit losses	5,682	10,073
Ending Balance	119,098	133,885	117,718
Time and Demand Loans
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(1,765)		(16,147)
Recoveries	347		260
Commercial Credit Cards
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(44)		(105)
Recoveries	0		13
Senior Lien
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(28)		(246)
Recoveries	43		177
Junior Lien
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(52)		(315)
Recoveries	16		70
Multifamily
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		0
Recoveries	0		0
Nonowner Occupied Commercial Real Estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(283)		(4,705)
Recoveries	44		127
Owner Occupied Commercial Real Estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		(1,572)
Recoveries	70		24
Automobiles
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(1,942)		(5,587)
Recoveries	553		1,832
Consumer Credit Cards
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(150)		(290)
Recoveries	18		87
Other Consumer Loans
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(446)		(1,353)
Recoveries	91		300
Construction Residential
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		0
Recoveries	0		0
Construction Other
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		0
Recoveries	6		0
Time and Demand Loans Other
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(502)		(2,410)
Recoveries	58		225
Equipment Finance
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(351)		(537)
Recoveries	15		0
Commercial, financial, agricultural and other [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	27,996	22,650	22,650
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		15,949
Charge-offs	(2,662)	(663)
Recoveries	420	159
Provision for credit losses	1,292	4,473
Ending Balance	27,046	42,568	27,996
Commercial, financial, agricultural and other [Member] | Time and Demand Loans
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	22,819	20,040	20,040
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		15,949
Charge-offs	(1,765)	(255)
Recoveries	347	116
Provision for credit losses	(565)	3,615
Ending Balance	20,836	39,465	22,819
Commercial, financial, agricultural and other [Member] | Commercial Credit Cards
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	278	335	335
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		0
Charge-offs	(44)	(26)
Recoveries	0	2
Provision for credit losses	71	20
Ending Balance	305	331	278
Commercial, financial, agricultural and other [Member] | Time and Demand Loans Other
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	1,500	1,189	1,189
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		0
Charge-offs	(502)	(337)
Recoveries	58	41
Provision for credit losses	523	418
Ending Balance	1,579	1,311	1,500
Commercial, financial, agricultural and other [Member] | Equipment Finance
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	3,399	1,086	1,086
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		0
Charge-offs	(351)	(45)
Recoveries	15	0
Provision for credit losses	1,263	420
Ending Balance	4,326	1,461	3,399
Residential real estate [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	23,901	21,412	21,412
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		527
Charge-offs	(80)	(79)
Recoveries	59	38
Provision for credit losses	13	875
Ending Balance	23,893	22,773	23,901
Residential real estate [Member] | Senior Lien
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	16,975	14,822	14,822
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		197
Charge-offs	(28)	(16)
Recoveries	43	26
Provision for credit losses	(107)	795
Ending Balance	16,883	15,824	16,975
Residential real estate [Member] | Junior Lien
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	6,926	6,590	6,590
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		330
Charge-offs	(52)	(63)
Recoveries	16	12
Provision for credit losses	120	80
Ending Balance	7,010	6,949	6,926
Commercial Real Estate [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	37,071	28,804	28,804
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		5,313
Charge-offs	(283)	0
Recoveries	114	42
Provision for credit losses	2,201	5,218
Ending Balance	39,103	39,377	37,071
Commercial Real Estate [Member] | Multifamily
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	5,233	4,726	4,726
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		234
Charge-offs	0	0
Recoveries	0	0
Provision for credit losses	(8)	581
Ending Balance	5,225	5,541	5,233
Commercial Real Estate [Member] | Nonowner Occupied Commercial Real Estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	19,995	16,426	16,426
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		2,739
Charge-offs	(283)	0
Recoveries	44	38
Provision for credit losses	2,308	2,349
Ending Balance	22,064	21,552	19,995
Commercial Real Estate [Member] | Owner Occupied Commercial Real Estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	11,843	7,652	7,652
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		2,340
Charge-offs	0	0
Recoveries	70	4
Provision for credit losses	(99)	2,288
Ending Balance	11,814	12,284	11,843
Loans to individuals [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	21,332	21,218	21,218
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		3
Charge-offs	(2,538)	(1,141)
Recoveries	662	471
Provision for credit losses	3,051	667
Ending Balance	22,507	21,218	21,332
Loans to individuals [Member] | Automobiles
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	19,142	18,819	18,819
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		3
Charge-offs	(1,942)	(802)
Recoveries	553	390
Provision for credit losses	2,490	603
Ending Balance	20,243	19,013	19,142
Loans to individuals [Member] | Consumer Credit Cards
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	372	412	412
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		0
Charge-offs	(150)	(66)
Recoveries	18	17
Provision for credit losses	107	5
Ending Balance	347	368	372
Loans to individuals [Member] | Other Consumer Loans
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	1,818	1,987	1,987
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		0
Charge-offs	(446)	(273)
Recoveries	91	64
Provision for credit losses	454	59
Ending Balance	1,917	1,837	1,818
Real estate construction [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	7,418	8,822	8,822
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		287
Charge-offs	0	0
Recoveries	6	0
Provision for credit losses	(875)	(1,160)
Ending Balance	6,549	7,949	7,418
Real estate construction [Member] | Construction Residential
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	970	2,462	2,462
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		60
Charge-offs	0	0
Recoveries	0	0
Provision for credit losses	(222)	(464)
Ending Balance	748	2,058	970
Real estate construction [Member] | Construction Other
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	6,448	6,360	6,360
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		227
Charge-offs	0	0
Recoveries	6	0
Provision for credit losses	(653)	(696)
Ending Balance	$ 5,801	$ 5,891	$ 6,448