Loans Held for Investment and Allowance for Loan Losses - Schedule of Allowance for Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	$ 15,455		$ 17,870	$ 16,350
Loans collectively evaluated for credit losses	58,653		45,595	47,020
Total allowance for loan losses	74,108	$ 71,932	63,465	63,370	$ 62,138	$ 66,534
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	8,439		6,627	3,906
Loans collectively evaluated for credit losses	8,000		5,653	6,487
Total allowance for loan losses	16,439	18,589	12,280	10,393	10,186	13,609
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	0
Loans collectively evaluated for credit losses	1,319		348	315
Total allowance for loan losses	1,319	1,352	348	315	588	1,552
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	591		225	164
Loans collectively evaluated for credit losses	25,108		17,402	16,698
Total allowance for loan losses	25,699	21,085	17,627	16,862	15,632	13,512
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	41		2	6
Loans collectively evaluated for credit losses	1,114		661	580
Total allowance for loan losses	1,155	1,006	663	586	607	1,876
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	2,329		4,059	3,975
Loans collectively evaluated for credit losses	5,866		6,663	6,669
Total allowance for loan losses	8,195	8,410	10,722	10,644	10,432	8,391
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	2,061		3,481	3,481
Loans collectively evaluated for credit losses	8,025		7,347	7,408
Total allowance for loan losses	10,086	10,740	10,828	10,889	10,399	12,347
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	1,640		2,026	2,663
Loans collectively evaluated for credit losses	7,314		6,107	7,394
Total allowance for loan losses	8,954	8,304	8,133	10,057	11,234	12,601
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	3		4	4
Loans collectively evaluated for credit losses	909		892	956
Total allowance for loan losses	912	912	896	960	1,266	1,020
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	1		1	2
Loans collectively evaluated for credit losses	355		370	373
Total allowance for loan losses	356	372	371	375	482	371
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	350		1,445	2,149
Loans collectively evaluated for credit losses	643		152	140
Total allowance for loan losses	$ 993	$ 1,162	$ 1,597	$ 2,289	$ 1,312	$ 1,255