Loans Held for Investment and Allowance for Loan Losses - Schedule of Allowance for Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	$ 17,467		$ 17,870	$ 17,186
Loans collectively evaluated for credit losses	54,465		45,595	44,952
Total allowance for loan losses	71,932	$ 66,913	63,465	62,138	$ 62,974	$ 66,534
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	9,591		6,627	4,588
Loans collectively evaluated for credit losses	8,998		5,653	5,598
Total allowance for loan losses	18,589	15,737	12,280	10,186	12,323	13,609
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses				275
Loans collectively evaluated for credit losses	1,352		348	313
Total allowance for loan losses	1,352	1,418	348	588	2,191	1,552
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	386		225	1,099
Loans collectively evaluated for credit losses	20,699		17,402	14,533
Total allowance for loan losses	21,085	17,887	17,627	15,632	13,246	13,512
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	46		2	9
Loans collectively evaluated for credit losses	960		661	598
Total allowance for loan losses	1,006	873	663	607	1,223	1,876
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	2,843		4,059	4,200
Loans collectively evaluated for credit losses	5,567		6,663	6,232
Total allowance for loan losses	8,410	8,499	10,722	10,432	9,492	8,391
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	2,585		3,481	3,144
Loans collectively evaluated for credit losses	8,155		7,347	7,255
Total allowance for loan losses	10,740	11,536	10,828	10,399	9,878	12,347
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	1,652		2,026	2,609
Loans collectively evaluated for credit losses	6,652		6,107	8,625
Total allowance for loan losses	8,304	7,829	8,133	11,234	11,189	12,601
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	3		4	5
Loans collectively evaluated for credit losses	909		892	1,261
Total allowance for loan losses	912	869	896	1,266	1,068	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	371		370	480
Total allowance for loan losses	372	354	371	482	379	371
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for credit losses	360		1,445	1,255
Loans collectively evaluated for credit losses	802		152	57
Total allowance for loan losses	$ 1,162	$ 1,911	$ 1,597	$ 1,312	$ 1,985	$ 1,255