Loans Held for Investment and Allowance for Credit Losses on Loans - Age Analysis of Loans Held for Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 6,943,563	$ 6,169,442
Accruing Loans 90 Days or More Past Due	7,085	4,964
Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	261,518
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	6,943,563
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	906,461	775,554
Accruing Loans 90 Days or More Past Due	4,580	18
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,385,307	1,095,324
Accruing Loans 90 Days or More Past Due	43
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	481,070	415,466
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	304,432	254,524
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,119,706	937,006
Accruing Loans 90 Days or More Past Due	349	1,704
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	199,005	161,018
Accruing Loans 90 Days or More Past Due	166	431
Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	261,518	272,179
Accruing Loans 90 Days or More Past Due	114	139
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,376,375	1,416,093
Accruing Loans 90 Days or More Past Due	1,285	2,418
Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	447,039	413,370
Accruing Loans 90 Days or More Past Due	467	254
Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	462,650	428,908
30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	21,178	19,966
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	1,314	2,046
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	6,237	7,244
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	535	136
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	1,321	2,264
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	3,415	3,351
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	265	293
30 to 59 Days Past Due [Member] | Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,346	253
30 to 59 Days Past Due [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	3,500	2,506
30 to 59 Days Past Due [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,591	1,873
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	5,783	1,724
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	1,524	223
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	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	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	1,076	567
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	37	30
60 to 89 Days Past Due [Member] | Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		37
60 to 89 Days Past Due [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,176	546
60 to 89 Days Past Due [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	648	321
90 Days and Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	11,535	14,200
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	4,580	1,465
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	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	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	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	844	2,817
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	185	451
90 Days and Greater [Member] | Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	325	2,077
90 Days and Greater [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	4,712	7,118
90 Days and Greater [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	585	272
Past Due Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	38,496	35,890
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	7,418	3,734
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	6,279	7,244
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	689	136
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	1,751	2,264
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	5,335	6,735
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	487	774
Past Due Loans [Member] | Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,671	2,367
Past Due Loans [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	10,388	10,170
Past Due Loans [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	3,824	2,466
Past Due Loans [Member] | Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	654
Current Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	6,905,067	6,133,552
Current Loans [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	899,043	771,820
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	1,379,028	1,088,080
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	480,381	415,330
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	302,681	252,260
Current Loans [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,114,371	930,271
Current Loans [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	198,518	160,244
Current Loans [Member] | Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	259,847	269,812
Current Loans [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,365,987	1,405,923
Current Loans [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	443,215	410,904
Current Loans [Member] | Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	$ 461,996	$ 428,908