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	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	$ 152,160	$ 161,185	$ 190,416
Loans collectively evaluated for credit losses	5,414,009	5,227,787	5,132,146
Total Loans	5,566,169	5,388,972	5,322,562
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	25,331	24,391	19,289
Loans collectively evaluated for credit losses	812,718	812,684	1,158,837
Total Loans	838,049	837,075	1,178,126
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	96	109	9,777
Loans collectively evaluated for credit losses	191,703	177,796	167,172
Total Loans	191,799	177,905	176,949
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	10,226	5,473	12,497
Loans collectively evaluated for credit losses	795,985	744,320	575,431
Total Loans	806,211	749,793	587,928
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	2,423	3,142	10,295
Loans collectively evaluated for credit losses	223,519	214,078	151,751
Total Loans	225,942	217,220	162,046
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	35,279	34,468	39,387
Loans collectively evaluated for credit losses	600,881	588,966	610,757
Total Loans	636,160	623,434	650,144
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	36,896	48,504	55,450
Loans collectively evaluated for credit losses	844,285	773,149	704,456
Total Loans	881,181	821,653	759,906
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	35,276	37,570	34,695
Loans collectively evaluated for credit losses	1,316,886	1,296,849	1,220,032
Total Loans	1,352,162	1,334,419	1,254,727
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	1,494	1,675	1,716
Loans collectively evaluated for credit losses	418,324	403,741	368,311
Total Loans	419,818	405,416	370,027
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	390	455	451
Loans collectively evaluated for credit losses	131,574	123,513	91,892
Total Loans	131,964	123,968	92,343
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	1,029,848	1,014,980	1,355,075
Commercial [Member] | C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	838,049	837,075	1,178,126
Commercial [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	191,799	177,905	176,949
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	4,749	5,398	6,859
Loans collectively evaluated for credit losses	78,134	92,691	83,507
Total Loans	82,883	98,089	90,366
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	3,901,656	3,746,519	3,414,751
Real Estate [Member] | Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	806,211	749,793	587,928
Real Estate [Member] | Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	225,942	217,220	162,046
Real Estate [Member] | Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	636,160	623,434	650,144
Real Estate [Member] | Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	881,181	821,653	759,906
Real Estate [Member] | Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	1,352,162	1,334,419	1,254,727
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	551,782	529,384	462,370
Consumer [Member] | Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	419,818	405,416	370,027
Consumer [Member] | Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	$ 131,964	$ 123,968	$ 92,343