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, 2022	Dec. 31, 2021	Sep. 30, 2021
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		$ 143,717	$ 161,185	$ 165,771
Loans collectively evaluated for credit losses		6,111,771	5,227,787	5,120,723
Total Loans		6,255,488	5,388,972	5,286,494
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		26,810	24,391	22,143
Loans collectively evaluated for credit losses		844,525	812,684	797,454
Total Loans		871,335	837,075	819,597
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		71	109	121
Loans collectively evaluated for credit losses		214,781	177,796	165,726
Total Loans		214,852	177,905	165,847
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		7,157	5,473	6,327
Loans collectively evaluated for credit losses		930,894	744,320	650,203
Total Loans		938,051	749,793	656,530
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		1,707	3,142	3,105
Loans collectively evaluated for credit losses		266,432	214,078	199,959
Total Loans		268,139	217,220	203,064
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		35,365	34,468	36,158
Loans collectively evaluated for credit losses		682,373	588,966	638,800
Total Loans		717,738	623,434	674,958
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		36,839	48,504	49,332
Loans collectively evaluated for credit losses		908,826	773,149	774,899
Total Loans		945,665	821,653	824,231
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		32,838	37,570	38,489
Loans collectively evaluated for credit losses		1,503,342	1,296,849	1,290,309
Total Loans		1,536,180	1,334,419	1,328,798
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		1,692	1,675	1,770
Loans collectively evaluated for credit losses		537,106	403,741	392,302
Total Loans		538,798	405,416	394,072
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		488	455	433
Loans collectively evaluated for credit losses		147,305	123,513	120,017
Total Loans		147,793	123,968	120,450
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		1,086,187	1,014,980	985,444
Commercial [Member] | C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	[1]	871,335	837,075	819,597
Commercial [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		214,852	177,905	165,847
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses		750	5,398	7,893
Loans collectively evaluated for credit losses		76,187	92,691	91,054
Total Loans		76,937	98,089	98,947
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		4,405,773	3,746,519	3,687,581
Real Estate [Member] | Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		938,051	749,793	656,530
Real Estate [Member] | Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		268,139	217,220	203,064
Real Estate [Member] | Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		717,738	623,434	674,958
Real Estate [Member] | Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		945,665	821,653	824,231
Real Estate [Member] | Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		1,536,180	1,334,419	1,328,798
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		686,591	529,384	514,522
Consumer [Member] | Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		538,798	405,416	394,072
Consumer [Member] | Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans		$ 147,793	$ 123,968	$ 120,450

[1] All disclosures for the C&I loan segment include PPP loan balances, net of deferred fees and costs, as disclosed on the face of the consolidated balance sheet.