Loans and Allowance for Credit Losses - Loans by Credit Risk Rating, Segregated by Class of Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 15,110,344	$ 12,012,503
Loans other than pass or current
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,257,390	2,516,672
Fiscal year before current fiscal year	2,704,208	1,525,310
Two years before current fiscal year	1,350,794	709,683
Three years before current fiscal year	711,723	656,367
Four years before current fiscal year	632,317	801,918
Five years before current fiscal year	1,654,920	1,081,384
Lines of Credit (“LOC”) Amortized Cost Basis	5,732,774	4,431,020
LOC Converted to Term Loans Amortized Cost Basis	66,218	290,149
Total	15,110,344	12,012,503
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	394,376	355,370
Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Total	189,684	187,052
Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	204,692	168,318
Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	11,522,685	9,167,250
Real Estate | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,082,688	1,326,371
Real Estate | Construction and development | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	141,408	74,813
Fiscal year before current fiscal year	112,131	83,729
Two years before current fiscal year	82,372	28,803
Three years before current fiscal year	28,611	17,349
Four years before current fiscal year	21,030	8,505
Five years before current fiscal year	21,377	9,319
Lines of Credit (“LOC”) Amortized Cost Basis	1,669,088	1,074,617
LOC Converted to Term Loans Amortized Cost Basis	346	20,285
Total	2,076,363	1,317,420
Real Estate | Construction and development | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	270
Three years before current fiscal year	257	0
Four years before current fiscal year	0	0
Five years before current fiscal year	45	47
Lines of Credit (“LOC”) Amortized Cost Basis	0	0
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	302	317
Real Estate | Construction and development | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,955	191
Fiscal year before current fiscal year	91	77
Two years before current fiscal year	12	16
Three years before current fiscal year	14	54
Four years before current fiscal year	32	324
Five years before current fiscal year	151	423
Lines of Credit (“LOC”) Amortized Cost Basis	3,768	5,598
LOC Converted to Term Loans Amortized Cost Basis	0	1,951
Total	6,023	8,634
Real Estate | Construction and development | Doubtful and loss
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	0	0
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	0	0
Real Estate | Construction and development | Risk rate 5, 6, and 7
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	143,363	75,004
Fiscal year before current fiscal year	112,222	83,806
Two years before current fiscal year	82,384	29,089
Three years before current fiscal year	28,882	17,403
Four years before current fiscal year	21,062	8,829
Five years before current fiscal year	21,573	9,789
Lines of Credit (“LOC”) Amortized Cost Basis	1,672,856	1,080,215
LOC Converted to Term Loans Amortized Cost Basis	346	22,236
Total	2,082,688	1,326,371
Real Estate | Single family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,357,942	2,101,975
Real Estate | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	7,082,055	5,738,904
Real Estate | Other commercial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,122,003	1,349,746
Fiscal year before current fiscal year	1,607,077	807,701
Two years before current fiscal year	704,790	375,824
Three years before current fiscal year	389,165	267,696
Four years before current fiscal year	270,028	476,029
Five years before current fiscal year	870,569	537,493
Lines of Credit (“LOC”) Amortized Cost Basis	1,726,593	1,409,099
LOC Converted to Term Loans Amortized Cost Basis	19,805	164,856
Total	6,710,030	5,388,444
Real Estate | Other commercial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	32,585	28,151
Fiscal year before current fiscal year	13,784	30,981
Two years before current fiscal year	34,233	2,799
Three years before current fiscal year	2,815	6,650
Four years before current fiscal year	6,836	39,361
Five years before current fiscal year	30,804	4,801
Lines of Credit (“LOC”) Amortized Cost Basis	61,082	38,638
LOC Converted to Term Loans Amortized Cost Basis	0	1,608
Total	182,139	152,989
Real Estate | Other commercial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	37,988	28,137
Fiscal year before current fiscal year	19,126	10,186
Two years before current fiscal year	15,535	5,243
Three years before current fiscal year	4,606	10,806
Four years before current fiscal year	15,386	30,060
Five years before current fiscal year	47,629	27,107
Lines of Credit (“LOC”) Amortized Cost Basis	49,616	53,860
LOC Converted to Term Loans Amortized Cost Basis	0	32,072
Total	189,886	197,471
Real Estate | Other commercial | Doubtful and loss
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	0	0
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	0	0
Real Estate | Other commercial | Risk rate 5, 6, and 7
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,192,576	1,406,034
Fiscal year before current fiscal year	1,639,987	848,868
Two years before current fiscal year	754,558	383,866
Three years before current fiscal year	396,586	285,152
Four years before current fiscal year	292,250	545,450
Five years before current fiscal year	949,002	569,401
Lines of Credit (“LOC”) Amortized Cost Basis	1,837,291	1,501,597
LOC Converted to Term Loans Amortized Cost Basis	19,805	198,536
Total	7,082,055	5,738,904
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,830,999	2,160,760
Commercial | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,612,256	1,992,043
Commercial | Commercial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	390,270	455,499
Fiscal year before current fiscal year	403,212	187,517
Two years before current fiscal year	193,069	80,486
Three years before current fiscal year	87,732	57,437
Four years before current fiscal year	49,283	36,529
Five years before current fiscal year	75,417	57,099
Lines of Credit (“LOC”) Amortized Cost Basis	1,336,375	1,004,971
LOC Converted to Term Loans Amortized Cost Basis	38,411	41,885
Total	2,573,769	1,921,423
Commercial | Commercial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	88	670
Fiscal year before current fiscal year	1,266	2,482
Two years before current fiscal year	120	1,066
Three years before current fiscal year	70	189
Four years before current fiscal year	11	261
Five years before current fiscal year	1,022	2,770
Lines of Credit (“LOC”) Amortized Cost Basis	3,596	8,500
LOC Converted to Term Loans Amortized Cost Basis	0	10,499
Total	6,173	26,437
Commercial | Commercial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,541	3,436
Fiscal year before current fiscal year	4,792	18,381
Two years before current fiscal year	796	4,397
Three years before current fiscal year	1,389	1,196
Four years before current fiscal year	2,334	578
Five years before current fiscal year	5,432	850
Lines of Credit (“LOC”) Amortized Cost Basis	14,098	8,242
LOC Converted to Term Loans Amortized Cost Basis	931	7,103
Total	32,313	44,183
Commercial | Commercial | Doubtful and loss
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	0	0
LOC Converted to Term Loans Amortized Cost Basis	1	0
Total	1	0
Commercial | Commercial | Risk rate 5, 6, and 7
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	392,899	459,605
Fiscal year before current fiscal year	409,270	208,380
Two years before current fiscal year	193,985	85,949
Three years before current fiscal year	89,191	58,822
Four years before current fiscal year	51,628	37,368
Five years before current fiscal year	81,871	60,719
Lines of Credit (“LOC”) Amortized Cost Basis	1,354,069	1,021,713
LOC Converted to Term Loans Amortized Cost Basis	39,343	59,487
Total	2,612,256	1,992,043
Commercial | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Total	218,743	168,717
Commercial | Agricultural | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	25,266	32,780
Fiscal year before current fiscal year	27,616	20,230
Two years before current fiscal year	13,144	10,253
Three years before current fiscal year	7,172	3,646
Four years before current fiscal year	1,832	2,364
Five years before current fiscal year	1,942	459
Lines of Credit (“LOC”) Amortized Cost Basis	140,470	98,245
LOC Converted to Term Loans Amortized Cost Basis	558	327
Total	218,000	168,304
Commercial | Agricultural | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	0	0
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	0	0
Commercial | Agricultural | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	191
Fiscal year before current fiscal year	58	25
Two years before current fiscal year	0	27
Three years before current fiscal year	99	53
Four years before current fiscal year	55	22
Five years before current fiscal year	1	3
Lines of Credit (“LOC”) Amortized Cost Basis	530	23
LOC Converted to Term Loans Amortized Cost Basis	0	69
Total	743	413
Commercial | Agricultural | Doubtful and loss
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	0	0
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	0	0
Commercial | Agricultural | Risk rate 5, 6, and 7
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	25,266	32,971
Fiscal year before current fiscal year	27,674	20,255
Two years before current fiscal year	13,144	10,280
Three years before current fiscal year	7,271	3,699
Four years before current fiscal year	1,887	2,386
Five years before current fiscal year	1,943	462
Lines of Credit (“LOC”) Amortized Cost Basis	141,000	98,268
LOC Converted to Term Loans Amortized Cost Basis	558	396
Total	218,743	168,717
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total	362,284	329,123
Current
Financing Receivable, Credit Quality Indicator [Line Items]
Total	15,051,177	11,958,874
Current | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	392,404	352,831
Current | Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	188,579	185,792
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	188,579	185,792
Current | Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	113,647	97,830
Fiscal year before current fiscal year	37,547	21,885
Two years before current fiscal year	15,582	11,712
Three years before current fiscal year	7,499	6,756
Four years before current fiscal year	4,689	5,416
Five years before current fiscal year	4,961	3,833
Lines of Credit (“LOC”) Amortized Cost Basis	19,897	19,607
LOC Converted to Term Loans Amortized Cost Basis	3	0
Total	203,825	167,039
Current | Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	11,479,038	9,131,179
Current | Real Estate | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,080,500	1,325,753
Current | Real Estate | Single family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	345,078	419,605
Fiscal year before current fiscal year	444,223	335,788
Two years before current fiscal year	281,134	185,190
Three years before current fiscal year	173,339	260,037
Four years before current fiscal year	234,911	193,110
Five years before current fiscal year	554,820	421,957
Lines of Credit (“LOC”) Amortized Cost Basis	296,238	256,155
LOC Converted to Term Loans Amortized Cost Basis	5,210	9,422
Total	2,334,953	2,081,264
Current | Real Estate | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	7,063,585	5,724,162
Current | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,817,464	2,145,744
Current | Commercial | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,598,906	1,977,157
Current | Commercial | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Total	218,558	168,587
Current | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	44,083	24,247
Fiscal year before current fiscal year	31,049	4,740
Two years before current fiscal year	9,005	1,236
Three years before current fiscal year	5,973	22,438
Four years before current fiscal year	23,119	6,692
Five years before current fiscal year	28,484	5,578
Lines of Credit (“LOC”) Amortized Cost Basis	219,605	264,189
LOC Converted to Term Loans Amortized Cost Basis	953	0
Total	362,271	329,120
30-89 days past due | Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	823	847
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	823	847
30-89 days past due | Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	121	265
Fiscal year before current fiscal year	308	121
Two years before current fiscal year	85	164
Three years before current fiscal year	59	49
Four years before current fiscal year	21	219
Five years before current fiscal year	173	156
Lines of Credit (“LOC”) Amortized Cost Basis	19	175
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	786	1,149
30-89 days past due | Real Estate | Single family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	357	1,061
Fiscal year before current fiscal year	1,492	883
Two years before current fiscal year	434	1,662
Three years before current fiscal year	2,311	791
Four years before current fiscal year	1,533	1,077
Five years before current fiscal year	5,348	4,360
Lines of Credit (“LOC”) Amortized Cost Basis	924	1,479
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	12,399	11,313
30-89 days past due | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	0	0
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	0	0
90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total	35,450	32,907
90+ days past due | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	363	543
90+ days past due | Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	282	413
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	282	413
90+ days past due | Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	23
Fiscal year before current fiscal year	17	23
Two years before current fiscal year	8	28
Three years before current fiscal year	5	21
Four years before current fiscal year	4	13
Five years before current fiscal year	39	22
Lines of Credit (“LOC”) Amortized Cost Basis	8	0
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	81	130
90+ days past due | Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	26,882	22,170
90+ days past due | Real Estate | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,610	504
90+ days past due | Real Estate | Single family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	27
Fiscal year before current fiscal year	419	561
Two years before current fiscal year	475	507
Three years before current fiscal year	607	1,199
Four years before current fiscal year	1,213	1,358
Five years before current fiscal year	6,693	5,104
Lines of Credit (“LOC”) Amortized Cost Basis	1,183	570
LOC Converted to Term Loans Amortized Cost Basis	0	72
Total	10,590	9,398
90+ days past due | Real Estate | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	14,682	12,268
90+ days past due | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	8,192	10,191
90+ days past due | Commercial | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	8,148	10,074
90+ days past due | Commercial | Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Total	44	117
90+ days past due | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	13	3
Lines of Credit (“LOC”) Amortized Cost Basis	0	0
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	13	3
30 + days past due | Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Five years before current fiscal year	0	0
Lines of Credit (“LOC”) Amortized Cost Basis	189,684	187,052
LOC Converted to Term Loans Amortized Cost Basis	0	0
Total	189,684	187,052
30 + days past due | Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	113,768	98,118
Fiscal year before current fiscal year	37,872	22,029
Two years before current fiscal year	15,675	11,904
Three years before current fiscal year	7,563	6,826
Four years before current fiscal year	4,714	5,648
Five years before current fiscal year	5,173	4,011
Lines of Credit (“LOC”) Amortized Cost Basis	19,924	19,782
LOC Converted to Term Loans Amortized Cost Basis	3	0
Total	204,692	168,318
30 + days past due | Real Estate | Single family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	345,435	420,693
Fiscal year before current fiscal year	446,134	337,232
Two years before current fiscal year	282,043	187,359
Three years before current fiscal year	176,257	262,027
Four years before current fiscal year	237,657	195,545
Five years before current fiscal year	566,861	431,421
Lines of Credit (“LOC”) Amortized Cost Basis	298,345	258,204
LOC Converted to Term Loans Amortized Cost Basis	5,210	9,494
Total	2,357,942	2,101,975
30 + days past due | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	44,083	24,247
Fiscal year before current fiscal year	31,049	4,740
Two years before current fiscal year	9,005	1,236
Three years before current fiscal year	5,973	22,438
Four years before current fiscal year	23,119	6,692
Five years before current fiscal year	28,497	5,581
Lines of Credit (“LOC”) Amortized Cost Basis	219,605	264,189
LOC Converted to Term Loans Amortized Cost Basis	953	0
Total	$ 362,284	$ 329,123