Loans Held for Investment and Allowance for Loan Losses - Schedule of Investment in Loans Related to Balance in Allowance for Loan Losses on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	$ 229,923	$ 176,213	$ 179,105
Loans collectively evaluated for credit losses	7,493,268	6,972,578	6,815,591
Total Loans	7,723,191	7,148,791	6,994,696
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	25,237	22,765	23,841
Loans collectively evaluated for credit losses	1,150,537	1,142,046	1,084,399
Total Loans	1,175,774	1,164,811	1,108,240
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	373	733	1,377
Loans collectively evaluated for credit losses	333,359	214,117	216,981
Total Loans	333,732	214,850	218,358
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	10,021	23,989	23,207
Loans collectively evaluated for credit losses	1,003,789	939,169	906,363
Total Loans	1,013,810	963,158	929,570
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	10,324	6,166	7,759
Loans collectively evaluated for credit losses	305,396	338,788	333,293
Total Loans	315,720	344,954	341,052
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	38,394	37,139	36,534
Loans collectively evaluated for credit losses	787,534	790,830	792,366
Total Loans	825,928	827,969	828,900
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	86,775	42,568	42,800
Loans collectively evaluated for credit losses	999,975	994,713	960,113
Total Loans	1,086,750	1,037,281	1,002,913
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	51,180	37,906	38,443
Loans collectively evaluated for credit losses	2,061,016	1,796,687	1,750,470
Total Loans	2,112,196	1,834,593	1,788,913
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	3,108	2,589	2,323
Loans collectively evaluated for credit losses	614,995	519,270	538,059
Total Loans	618,103	521,859	540,382
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	1,273	899	705
Loans collectively evaluated for credit losses	156,636	153,527	153,787
Total Loans	157,909	154,426	154,492
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	3,238	1,459	2,116
Loans collectively evaluated for credit losses	80,031	83,431	79,760
Total Loans	83,269	84,890	81,876
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	5,354,404	5,007,955	4,891,348
Real Estate [Member] | Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	1,013,810	963,158	929,570
Real Estate [Member] | Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	315,720	344,954	341,052
Real Estate [Member] | Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	825,928	827,969	828,900
Real Estate [Member] | Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	1,086,750	1,037,281	1,002,913
Real Estate [Member] | Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	2,112,196	1,834,593	1,788,913
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	776,012	676,285	694,874
Consumer [Member] | Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	618,103	521,859	540,382
Consumer [Member] | Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	$ 157,909	$ 154,426	$ 154,492