Loans Held for Investment and Allowance for Credit Losses on Loans - Age Analysis of Loans Held for Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 7,656,645	$ 6,943,563
Accruing Loans 90 Days or More Past Due	9,542	7,085
Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	427,139	408,037
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	7,656,645	6,943,563
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	960,944	908,494
Accruing Loans 90 Days or More Past Due	4,377	4,580
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,486,420	1,383,150
Accruing Loans 90 Days or More Past Due	913	43
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	642,643	475,236
Accruing Loans 90 Days or More Past Due		81
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	283,486	303,305
Accruing Loans 90 Days or More Past Due	332
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,258,744	1,117,899
Accruing Loans 90 Days or More Past Due	731	349
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	244,696	196,198
Accruing Loans 90 Days or More Past Due	549	166
Real Estate [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	427,139	408,037
Accruing Loans 90 Days or More Past Due	579	1,054
Commercial Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,289,452	1,241,454
Accruing Loans 90 Days or More Past Due	1,714	345
Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	476,467	446,756
Accruing Loans 90 Days or More Past Due	347	467
Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	586,654	463,034
30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	16,429	21,178
30 to 59 Days Past Due [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,386	1,314
30 to 59 Days Past Due [Member] | Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,224	6,237
30 to 59 Days Past Due [Member] | Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	198	535
30 to 59 Days Past Due [Member] | Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,542	1,320
30 to 59 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	3,879	3,415
30 to 59 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	757	265
30 to 59 Days Past Due [Member] | Real Estate [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,694	2,357
30 to 59 Days Past Due [Member] | Commercial Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,501	2,490
30 to 59 Days Past Due [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	3,248	2,591
30 to 59 Days Past Due [Member] | Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		654
60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	11,405	5,783
60 to 89 Days Past Due [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	26	1,524
60 to 89 Days Past Due [Member] | Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	7,371
60 to 89 Days Past Due [Member] | Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	158	40
60 to 89 Days Past Due [Member] | Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	206	282
60 to 89 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,204	1,076
60 to 89 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	190	37
60 to 89 Days Past Due [Member] | Real Estate [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	724	34
60 to 89 Days Past Due [Member] | Commercial Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	436	2,142
60 to 89 Days Past Due [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,090	648
90 Days and Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	22,992	11,535
90 Days and Greater [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	5,598	4,580
90 Days and Greater [Member] | Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,786	42
90 Days and Greater [Member] | Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	800	114
90 Days and Greater [Member] | Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	405	148
90 Days and Greater [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,849	844
90 Days and Greater [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	613	185
90 Days and Greater [Member] | Real Estate [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,227	2,265
90 Days and Greater [Member] | Commercial Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	10,028	2,772
90 Days and Greater [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	594	585
90 Days and Greater [Member] | Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	92
Past Due Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	50,826	38,496
Past Due Loans [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	7,010	7,418
Past Due Loans [Member] | Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	11,381	6,279
Past Due Loans [Member] | Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,156	689
Past Due Loans [Member] | Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,153	1,750
Past Due Loans [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	6,932	5,335
Past Due Loans [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,560	487
Past Due Loans [Member] | Real Estate [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	3,645	4,656
Past Due Loans [Member] | Commercial Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	11,965	7,404
Past Due Loans [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	4,932	3,824
Past Due Loans [Member] | Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	92	654
Current Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	7,605,819	6,905,067
Current Loans [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	953,934	901,076
Current Loans [Member] | Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,475,039	1,376,871
Current Loans [Member] | Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	641,487	474,547
Current Loans [Member] | Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	281,333	301,555
Current Loans [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,251,812	1,112,564
Current Loans [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	243,136	195,711
Current Loans [Member] | Real Estate [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	423,494	403,381
Current Loans [Member] | Commercial Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,277,487	1,234,050
Current Loans [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	471,535	442,932
Current Loans [Member] | Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	$ 586,562	$ 462,380