Allowance for Credit Losses, Credit Quality and Other - Summary of Most Recent Analysis Performed, Risk Category of Loans by Class of Loans and Writeoffs (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2024	Dec. 31, 2023
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	$ 1,085,614	$ 2,138,730
Year Two	2,217,758	3,341,500
Year Three	3,235,526	2,083,044
Year Four	1,874,191	1,132,926
Year Five	973,604	872,429
Prior	3,416,284	2,908,528
Revolving Loans Amortized Cost Basis	1,978,480	1,947,571
Total	14,781,457	14,424,728
Writeoffs, Year One	1,390	3,252
Writeoffs, Year Two	686	490
Writeoffs, Year Three	228	1,351
Writeoffs, Year Four	1,122	1,072
Writeoffs, Year Five	138	2,878
Writeoffs, Prior	746	6,357
Writeoffs, Revolving	2,766	655
Writeoffs, Total	7,076	16,055
Commercial real estate loans
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	598,496	930,022
Year Two	1,100,853	2,146,390
Year Three	2,013,543	1,262,133
Year Four	1,167,143	626,807
Year Five	506,053	481,164
Prior	2,184,344	1,905,250
Revolving Loans Amortized Cost Basis	886,771	816,391
Total	8,457,203	8,168,157
Commercial real estate loans \| Non-farm/non-residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	246,380	388,831
Year Two	496,032	1,150,598
Year Three	1,001,891	830,588
Year Four	849,486	491,298
Year Five	407,839	404,822
Prior	2,002,645	1,747,135
Revolving Loans Amortized Cost Basis	595,652	536,682
Total	5,599,925	5,549,954
Writeoffs, Year One	0	0
Writeoffs, Year Two	0	0
Writeoffs, Year Three	0	0
Writeoffs, Year Four	780	0
Writeoffs, Year Five	1	1,826
Writeoffs, Prior	383	502
Writeoffs, Revolving	0	0
Writeoffs, Total	1,164	2,328
Commercial real estate loans \| Construction/land development
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	315,464	501,215
Year Two	559,633	926,208
Year Three	945,683	384,657
Year Four	276,770	88,901
Year Five	60,426	55,857
Prior	93,863	81,216
Revolving Loans Amortized Cost Basis	259,978	254,993
Total	2,511,817	2,293,047
Writeoffs, Year One	0	0
Writeoffs, Year Two	0	2
Writeoffs, Year Three	0	168
Writeoffs, Year Four	48	5
Writeoffs, Year Five	1	0
Writeoffs, Prior	32	88
Writeoffs, Revolving	0	0
Writeoffs, Total	81	263
Commercial real estate loans \| Agricultural
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	36,652	39,976
Year Two	45,188	69,584
Year Three	65,969	46,888
Year Four	40,887	46,608
Year Five	37,788	20,485
Prior	87,836	76,899
Revolving Loans Amortized Cost Basis	31,141	24,716
Total	345,461	325,156
Writeoffs, Year One	0	0
Writeoffs, Year Two	0	0
Writeoffs, Year Three	0	0
Writeoffs, Year Four	0	0
Writeoffs, Year Five	0	1
Writeoffs, Prior	0	6
Writeoffs, Revolving	0	0
Writeoffs, Total	0	7
Residential real estate loans \| Residential 1-4 family
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	127,293	261,784
Year Two	245,489	409,197
Year Three	430,665	300,563
Year Four	268,374	171,122
Year Five	162,118	111,327
Prior	471,659	403,729
Revolving Loans Amortized Cost Basis	204,545	186,538
Total	1,910,143	1,844,260
Writeoffs, Year One	0	0
Writeoffs, Year Two	1	29
Writeoffs, Year Three	101	28
Writeoffs, Year Four	0	73
Writeoffs, Year Five	26	13
Writeoffs, Prior	90	126
Writeoffs, Revolving	0	0
Writeoffs, Total	218	269
Residential real estate loans \| Multifamily residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	56,867	3,983
Year Two	3,982	87,012
Year Three	147,697	107,301
Year Four	75,240	108,702
Year Five	101,535	39,815
Prior	101,928	74,564
Revolving Loans Amortized Cost Basis	21,842	14,359
Total	509,091	435,736
Total real estate
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	782,656	1,195,789
Year Two	1,350,324	2,642,599
Year Three	2,591,905	1,669,997
Year Four	1,510,757	906,631
Year Five	769,706	632,306
Prior	2,757,931	2,383,543
Revolving Loans Amortized Cost Basis	1,113,158	1,017,288
Total	10,876,437	10,448,153
Writeoffs, Year One	0	0
Writeoffs, Year Two	1	31
Writeoffs, Year Three	101	196
Writeoffs, Year Four	828	78
Writeoffs, Year Five	28	1,840
Writeoffs, Prior	505	722
Writeoffs, Revolving	0	0
Writeoffs, Total	1,463	2,867
Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	140,612	255,930
Year Two	232,030	257,588
Year Three	239,748	216,645
Year Four	194,632	109,981
Year Five	98,793	110,406
Prior	280,765	200,071
Revolving Loans Amortized Cost Basis	2,806	3,069
Total	1,189,386	1,153,690
Writeoffs, Year One	4	0
Writeoffs, Year Two	57	51
Writeoffs, Year Three	56	44
Writeoffs, Year Four	36	98
Writeoffs, Year Five	105	63
Writeoffs, Prior	139	263
Writeoffs, Revolving	0	25
Writeoffs, Total	397	544
Commercial and industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	113,216	619,371
Year Two	576,452	385,376
Year Three	353,826	156,919
Year Four	133,211	88,094
Year Five	79,251	114,522
Prior	321,820	276,677
Revolving Loans Amortized Cost Basis	664,296	684,032
Total	2,242,072	2,324,991
Writeoffs, Year One	0	0
Writeoffs, Year Two	557	407
Writeoffs, Year Three	71	1,110
Writeoffs, Year Four	258	894
Writeoffs, Year Five	5	911
Writeoffs, Prior	102	5,369
Writeoffs, Revolving	2,766	466
Writeoffs, Total	3,759	9,157
Agricultural & other
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	49,130	67,640
Year Two	58,952	55,937
Year Three	50,047	39,483
Year Four	35,591	28,220
Year Five	25,854	15,195
Prior	55,768	48,237
Revolving Loans Amortized Cost Basis	198,220	243,182
Total	473,562	497,894
Writeoffs, Year One	1,386	3,252
Writeoffs, Year Two	71	1
Writeoffs, Year Three	0	1
Writeoffs, Year Four	0	2
Writeoffs, Year Five	0	64
Writeoffs, Prior	0	3
Writeoffs, Revolving	0	164
Writeoffs, Total	1,457	3,487
Risk rating 1 \| Commercial real estate loans \| Non-farm/non-residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	232
Prior	337	116
Revolving Loans Amortized Cost Basis	100	55
Total	437	403
Risk rating 1 \| Commercial real estate loans \| Construction/land development
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	10
Year Four	10	0
Year Five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Total	10	10
Risk rating 1 \| Commercial real estate loans \| Agricultural
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	700	0
Year Two	0	1,605
Year Three	1,514	0
Year Four	0	0
Year Five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Total	2,214	1,605
Risk rating 1 \| Residential real estate loans \| Residential 1-4 family
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior	94	144
Revolving Loans Amortized Cost Basis	2	2
Total	96	146
Risk rating 1 \| Residential real estate loans \| Multifamily residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Total	0	0
Risk rating 1 \| Total real estate
Financing Receivable Allowance For Credit Losses [Line Items]
Year One		1,195,789
Year Two		2,642,599
Year Three		1,669,997
Year Four		906,631
Year Five		632,306
Prior		2,383,543
Revolving Loans Amortized Cost Basis		1,017,288
Total		10,448,153
Risk rating 1 \| Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	3,316	5,195
Year Two	3,156	2,952
Year Three	2,208	2,002
Year Four	1,597	839
Year Five	711	355
Prior	1,152	1,114
Revolving Loans Amortized Cost Basis	1,412	1,580
Total	13,552	14,037
Risk rating 1 \| Commercial and industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	2,809	3,757
Year Two	1,653	918
Year Three	825	1,120
Year Four	723	236
Year Five	225	121
Prior	21,356	20,835
Revolving Loans Amortized Cost Basis	10,686	12,644
Total	38,277	39,631
Risk rating 1 \| Agricultural & other
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	818	408
Year Two	397	131
Year Three	120	16
Year Four	16	105
Year Five	105	0
Prior	0	2
Revolving Loans Amortized Cost Basis	532	563
Total	1,988	1,225
Risk rating 2 \| Commercial real estate loans \| Non-farm/non-residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	111
Prior	107	0
Revolving Loans Amortized Cost Basis	0	0
Total	107	111
Risk rating 2 \| Commercial real estate loans \| Construction/land development
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	759
Year Two	137	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior	172	186
Revolving Loans Amortized Cost Basis	0	0
Total	309	945
Risk rating 2 \| Commercial real estate loans \| Agricultural
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	280	247
Year Two	0	0
Year Three	0	1,936
Year Four	1,881	0
Year Five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Total	2,161	2,183
Risk rating 2 \| Residential real estate loans \| Residential 1-4 family
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	259
Year Two	243	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior	12	20
Revolving Loans Amortized Cost Basis	6	1
Total	261	280
Risk rating 2 \| Residential real estate loans \| Multifamily residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Total	0	0
Risk rating 2 \| Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	0
Year Two	0	0
Year Three	0	0
Year Four	0	0
Year Five	0	126
Prior	160	54
Revolving Loans Amortized Cost Basis	0	0
Total	160	180
Risk rating 2 \| Commercial and industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	50	174
Year Two	146	1,293
Year Three	1,148	220
Year Four	197	12
Year Five	7	164
Prior	21	218
Revolving Loans Amortized Cost Basis	1,434	963
Total	3,003	3,044
Risk rating 2 \| Agricultural & other
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	340	396
Year Two	306	28
Year Three	28	1
Year Four	0	0
Year Five	0	1,181
Prior	1,181	100
Revolving Loans Amortized Cost Basis	810	693
Total	2,665	2,399
Risk rating 3 \| Commercial real estate loans \| Non-farm/non-residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	159,400	305,742
Year Two	333,618	584,860
Year Three	586,086	568,413
Year Four	571,400	243,177
Year Five	234,210	216,746
Prior	1,062,803	934,111
Revolving Loans Amortized Cost Basis	251,992	440,414
Total	3,199,509	3,293,463
Risk rating 3 \| Commercial real estate loans \| Construction/land development
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	248,129	300,941
Year Two	376,645	499,984
Year Three	440,356	130,342
Year Four	97,052	62,134
Year Five	48,293	22,656
Prior	69,645	56,180
Revolving Loans Amortized Cost Basis	55,009	44,603
Total	1,335,129	1,116,840
Risk rating 3 \| Commercial real estate loans \| Agricultural
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	25,657	30,252
Year Two	244	43,291
Year Three	41,696	22,919
Year Four	19,434	25,992
Year Five	23,432	10,678
Prior	47,780	43,284
Revolving Loans Amortized Cost Basis	26,501	20,104
Total	184,744	196,520
Risk rating 3 \| Residential real estate loans \| Residential 1-4 family
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	121,211	246,462
Year Two	223,643	366,149
Year Three	379,047	241,985
Year Four	238,461	145,339
Year Five	137,141	93,751
Prior	379,860	324,569
Revolving Loans Amortized Cost Basis	122,666	122,950
Total	1,602,029	1,541,205
Risk rating 3 \| Residential real estate loans \| Multifamily residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	56,867	3,314
Year Two	3,289	9,827
Year Three	20,471	37,755
Year Four	37,276	44,407
Year Five	42,392	31,436
Prior	79,577	53,068
Revolving Loans Amortized Cost Basis	6,997	6,537
Total	246,869	186,344
Risk rating 3 \| Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	135,047	240,897
Year Two	216,100	245,543
Year Three	228,339	211,312
Year Four	191,597	108,009
Year Five	97,199	108,063
Prior	270,424	191,220
Revolving Loans Amortized Cost Basis	1,169	1,264
Total	1,139,875	1,106,308
Risk rating 3 \| Commercial and industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	51,250	487,896
Year Two	529,271	272,608
Year Three	247,437	78,507
Year Four	67,550	50,340
Year Five	55,698	77,761
Prior	215,339	170,610
Revolving Loans Amortized Cost Basis	233,385	227,043
Total	1,399,930	1,364,765
Risk rating 3 \| Agricultural & other
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	35,973	52,758
Year Two	51,607	45,796
Year Three	39,854	31,378
Year Four	29,392	26,918
Year Five	24,999	3,059
Prior	40,000	43,984
Revolving Loans Amortized Cost Basis	135,539	145,419
Total	357,364	349,312
Risk rating 4 \| Commercial real estate loans \| Non-farm/non-residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	86,980	83,089
Year Two	162,414	557,540
Year Three	407,638	242,217
Year Four	266,750	224,378
Year Five	149,629	149,258
Prior	706,573	590,864
Revolving Loans Amortized Cost Basis	343,145	95,360
Total	2,123,129	1,942,706
Risk rating 4 \| Commercial real estate loans \| Construction/land development
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	67,335	198,874
Year Two	182,148	417,244
Year Three	502,703	252,602
Year Four	178,296	22,713
Year Five	11,237	32,342
Prior	23,070	24,527
Revolving Loans Amortized Cost Basis	204,026	209,063
Total	1,168,815	1,157,365
Risk rating 4 \| Commercial real estate loans \| Agricultural
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	10,015	9,477
Year Two	35,580	24,688
Year Three	22,759	20,358
Year Four	17,951	19,532
Year Five	13,272	7,873
Prior	38,084	32,692
Revolving Loans Amortized Cost Basis	4,640	4,612
Total	142,301	119,232
Risk rating 4 \| Residential real estate loans \| Residential 1-4 family
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	6,082	14,992
Year Two	19,129	37,444
Year Three	43,260	55,406
Year Four	26,204	21,240
Year Five	20,053	13,313
Prior	74,332	67,084
Revolving Loans Amortized Cost Basis	80,322	62,356
Total	269,382	271,835
Risk rating 4 \| Residential real estate loans \| Multifamily residential
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	0	669
Year Two	693	77,185
Year Three	127,076	69,546
Year Four	37,964	64,295
Year Five	59,143	8,116
Prior	22,109	18,490
Revolving Loans Amortized Cost Basis	14,845	7,822
Total	261,830	246,123
Risk rating 4 \| Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	2,241	9,597
Year Two	7,435	7,534
Year Three	7,726	2,479
Year Four	836	69
Year Five	32	109
Prior	5,622	6,073
Revolving Loans Amortized Cost Basis	200	214
Total	24,092	26,075
Risk rating 4 \| Commercial and industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Year One	59,084	115,025
Year Two	32,995	34,474
Year Three	32,387	55,812
Year Four	43,482	33,000
Year Five	19,359	27,189
Prior	71,144	71,854

Allowance for Credit Losses, Credit Quality and Other - Summary of Most Recent Analysis Performed, Risk Category of Loans by Class of Loans and Writeoffs (Detail) - USD ($)
$ in Thousands