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Loans and Allowance for Credit Losses - Credit Risk Profile of Loan Portfolio on Amortized Cost Basis Based on Risk Rating Category (Details) - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020
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Credit Quality Information [Abstract] |  |
Current fiscal year | $ 311,283 | $ 1,085,080
Fiscal year before current fiscal year | 1,362,003 | 558,953
Two years before current fiscal year | 666,851 | 386,847
Three years before current fiscal year | 478,577 | 300,829
Four years before current fiscal year | 330,702 | 247,242
Prior | 758,424 | 517,313
Revolving Loans | 35,259 | 42,155
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 3,943,099 | 3,138,419
Pass |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 293,386 | 1,052,257
Fiscal year before current fiscal year | 1,349,288 | 511,427
Two years before current fiscal year | 618,277 | 367,652
Three years before current fiscal year | 463,515 | 279,274
Four years before current fiscal year | 308,277 | 230,730
Prior | 691,797 | 459,453
Revolving Loans | 34,265 | 40,363
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 3,758,805 | 2,941,156
Special Mention |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 17,058 | 29,692
Fiscal year before current fiscal year | 10,208 | 44,049
Two years before current fiscal year | 45,041 | 8,731
Three years before current fiscal year | 5,078 | 15,165
Four years before current fiscal year | 14,870 | 9,344
Prior | 34,063 | 30,525
Revolving Loans | 57 | 293
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 126,375 | 137,799
Substandard |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 839 | 3,131
Fiscal year before current fiscal year | 2,507 | 3,477
Two years before current fiscal year | 3,533 | 10,464
Three years before current fiscal year | 9,984 | 6,390
Four years before current fiscal year | 7,555 | 7,168
Prior | 32,564 | 27,335
Revolving Loans | 937 | 1,499
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 57,919 | 59,464
Agricultural Loans |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 15,629 | 104,515
Fiscal year before current fiscal year | 87,163 | 20,401
Two years before current fiscal year | 10,808 | 6,697
Three years before current fiscal year | 5,370 | 2,062
Four years before current fiscal year | 1,837 | 783
Prior | 263 | 2,894
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 121,070 | 137,352
Agricultural Loans | Pass |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 1,853 | 83,377
Fiscal year before current fiscal year | 83,342 | 15,680
Two years before current fiscal year | 6,921 | 5,978
Three years before current fiscal year | 5,131 | 1,838
Four years before current fiscal year | 1,631 | 635
Prior | 104 | 2,856
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 98,982 | 110,364
Agricultural Loans | Special Mention |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 13,723 | 21,070
Fiscal year before current fiscal year | 3,777 | 4,483
Two years before current fiscal year | 3,769 | 694
Three years before current fiscal year | 214 | 224
Four years before current fiscal year | 206 | 148
Prior | 159 | 38
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 21,848 | 26,657
Agricultural Loans | Substandard |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 53 | 68
Fiscal year before current fiscal year | 44 | 238
Two years before current fiscal year | 118 | 25
Three years before current fiscal year | 25 | 0
Four years before current fiscal year | 0 | 0
Prior | 0 | 0
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 240 | 331
Consumer Loans |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 7,736 | 31,624
Fiscal year before current fiscal year | 35,935 | 21,424
Two years before current fiscal year | 33,343 | 12,219
Three years before current fiscal year | 11,637 | 8,375
Four years before current fiscal year | 217 | 3,218
Prior | 2,837 | 1,142
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 91,705 | 78,002
Consumer Loans | Pass |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 7,723 | 31,609
Fiscal year before current fiscal year | 35,908 | 21,384
Two years before current fiscal year | 33,307 | 12,084
Three years before current fiscal year | 11,526 | 8,279
Four years before current fiscal year | 138 | 3,150
Prior | 2,681 | 1,022
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 91,283 | 77,528
Consumer Loans | Special Mention |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 0 | 0
Fiscal year before current fiscal year | 0 | 24
Two years before current fiscal year | 23 | 24
Three years before current fiscal year | 21 | 1
Four years before current fiscal year | 0 | 1
Prior | 0 | 0
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 44 | 50
Consumer Loans | Substandard |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 13 | 15
Fiscal year before current fiscal year | 27 | 16
Two years before current fiscal year | 13 | 111
Three years before current fiscal year | 90 | 95
Four years before current fiscal year | 79 | 67
Prior | 156 | 120
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 378 | 424
Commercial and Industrial Loans |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 154,044 | 376,688
Fiscal year before current fiscal year | 480,758 | 166,638
Two years before current fiscal year | 198,271 | 71,878
Three years before current fiscal year | 99,775 | 81,068
Four years before current fiscal year | 98,877 | 43,676
Prior | 150,232 | 116,603
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 1,181,957 | 856,551
Commercial and Industrial Loans | Pass |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 152,091 | 371,683
Fiscal year before current fiscal year | 477,167 | 132,148
Two years before current fiscal year | 162,411 | 70,497
Three years before current fiscal year | 98,524 | 78,890
Four years before current fiscal year | 96,059 | 42,439
Prior | 145,657 | 114,904
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 1,131,909 | 810,561
Commercial and Industrial Loans | Special Mention |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 1,556 | 4,116
Fiscal year before current fiscal year | 3,248 | 32,130
Two years before current fiscal year | 33,491 | 849
Three years before current fiscal year | 804 | 489
Four years before current fiscal year | 473 | 1,101
Prior | 1,895 | 730
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 41,467 | 39,415
Commercial and Industrial Loans | Substandard |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 397 | 889
Fiscal year before current fiscal year | 343 | 2,360
Two years before current fiscal year | 2,369 | 532
Three years before current fiscal year | 447 | 1,689
Four years before current fiscal year | 2,345 | 136
Prior | 2,680 | 969
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 8,581 | 6,575
Real Estate Loan |  |
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 2,548,367 | 2,066,514
Real Estate Loan | Construction and Land Development |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 6,259 | 41,842
Fiscal year before current fiscal year | 55,930 | 41,117
Two years before current fiscal year | 35,910 | 31,500
Three years before current fiscal year | 44,866 | 3,277
Four years before current fiscal year | 12,641 | 871
Prior | 9,770 | 3,872
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 165,376 | 122,479
Real Estate Loan | Construction and Land Development | Pass |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 6,259 | 41,842
Fiscal year before current fiscal year | 55,930 | 40,989
Two years before current fiscal year | 35,782 | 31,500
Three years before current fiscal year | 44,866 | 2,760
Four years before current fiscal year | 12,068 | 871
Prior | 9,723 | 3,822
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 164,628 | 121,784
Real Estate Loan | Construction and Land Development | Special Mention |  |
Credit Quality Information [Abstract] |  |
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
Prior | 0 | 0
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 0 | 0
Real Estate Loan | Construction and Land Development | Substandard |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 0 | 0
Fiscal year before current fiscal year | 0 | 128
Two years before current fiscal year | 128 | 0
Three years before current fiscal year | 0 | 517
Four years before current fiscal year | 573 | 0
Prior | 47 | 50
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 748 | 695
Real Estate Loan | Agricultural |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 30,356 | 75,475
Fiscal year before current fiscal year | 101,331 | 38,382
Two years before current fiscal year | 35,419 | 39,172
Three years before current fiscal year | 41,060 | 16,815
Four years before current fiscal year | 15,749 | 14,729
Prior | 45,737 | 69,768
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 269,652 | 254,341
Real Estate Loan | Agricultural | Pass |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 29,531 | 73,630
Fiscal year before current fiscal year | 101,049 | 34,412
Two years before current fiscal year | 31,082 | 37,839
Three years before current fiscal year | 39,931 | 16,138
Four years before current fiscal year | 14,717 | 13,559
Prior | 38,968 | 58,291
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 255,278 | 233,869
Real Estate Loan | Agricultural | Special Mention |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 825 | 1,845
Fiscal year before current fiscal year | 282 | 3,970
Two years before current fiscal year | 4,337 | 533
Three years before current fiscal year | 422 | 469
Four years before current fiscal year | 407 | 1,106
Prior | 6,472 | 11,232
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 12,745 | 19,155
Real Estate Loan | Agricultural | Substandard |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 0 | 0
Fiscal year before current fiscal year | 0 | 0
Two years before current fiscal year | 0 | 800
Three years before current fiscal year | 707 | 208
Four years before current fiscal year | 625 | 64
Prior | 297 | 245
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 1,629 | 1,317
Real Estate Loan | Commercial |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 67,998 | 373,082
Fiscal year before current fiscal year | 485,480 | 238,459
Two years before current fiscal year | 320,122 | 184,780
Three years before current fiscal year | 233,337 | 161,567
Four years before current fiscal year | 176,487 | 155,046
Prior | 417,445 | 250,998
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 1,700,869 | 1,363,932
Real Estate Loan | Commercial | Pass |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 67,044 | 368,750
Fiscal year before current fiscal year | 480,974 | 237,119
Two years before current fiscal year | 318,800 | 171,591
Three years before current fiscal year | 223,168 | 148,283
Four years before current fiscal year | 163,413 | 143,400
Prior | 377,041 | 215,616
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 1,630,440 | 1,284,759
Real Estate Loan | Commercial | Special Mention |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 954 | 2,469
Fiscal year before current fiscal year | 2,712 | 1,300
Two years before current fiscal year | 1,285 | 6,108
Three years before current fiscal year | 3,268 | 11,262
Four years before current fiscal year | 11,070 | 6,741
Prior | 24,347 | 16,947
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 43,636 | 44,827
Real Estate Loan | Commercial | Substandard |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 0 | 1,863
Fiscal year before current fiscal year | 1,794 | 40
Two years before current fiscal year | 37 | 7,081
Three years before current fiscal year | 6,901 | 2,022
Four years before current fiscal year | 2,004 | 4,905
Prior | 16,057 | 18,435
Revolving Loans | 0 | 0
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 26,793 | 34,346
1-4 Family | Real Estate Loan | Residential Properties |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 29,261 | 81,854
Fiscal year before current fiscal year | 115,406 | 32,532
Two years before current fiscal year | 32,978 | 40,601
Three years before current fiscal year | 42,532 | 27,665
Four years before current fiscal year | 24,894 | 28,919
Prior | 132,140 | 72,036
Revolving Loans | 35,259 | 42,155
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 412,470 | 325,762
1-4 Family | Real Estate Loan | Residential Properties | Pass |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 28,885 | 81,366
Fiscal year before current fiscal year | 114,918 | 29,695
Two years before current fiscal year | 29,974 | 38,163
Three years before current fiscal year | 40,369 | 23,086
Four years before current fiscal year | 20,251 | 26,676
Prior | 117,623 | 62,942
Revolving Loans | 34,265 | 40,363
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 386,285 | 302,291
1-4 Family | Real Estate Loan | Residential Properties | Special Mention |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 0 | 192
Fiscal year before current fiscal year | 189 | 2,142
Two years before current fiscal year | 2,136 | 523
Three years before current fiscal year | 349 | 2,720
Four years before current fiscal year | 2,714 | 247
Prior | 1,190 | 1,578
Revolving Loans | 57 | 293
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | 6,635 | 7,695
1-4 Family | Real Estate Loan | Residential Properties | Substandard |  |
Credit Quality Information [Abstract] |  |
Current fiscal year | 376 | 296
Fiscal year before current fiscal year | 299 | 695
Two years before current fiscal year | 868 | 1,915
Three years before current fiscal year | 1,814 | 1,859
Four years before current fiscal year | 1,929 | 1,996
Prior | 13,327 | 7,516
Revolving Loans | 937 | 1,499
Loans Receivable Aging Analysis [Abstract] |  |
Total Loans Receivable | $ 19,550 | $ 15,776

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