Loans Held for Investment and Allowance for Loan Losses - Schedule of loans that are individually evaluated for credit losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Financing Receivable, Impaired [Line Items]
Related Allowance	$ 15,455	$ 17,870	$ 16,350
Total Recorded Investment	143,717	161,185	165,771
Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	13,428	19,955	15,891
Recorded Investment With Allowance	11,157	11,697	9,319
Related Allowance	4,815	4,184	1,558
Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	10,640	13,686	14,792
Total Recorded Investment	119,132	129,533	140,561
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	8,439	6,627	3,906
Total Recorded Investment	26,881	24,500	22,264
Commercial [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	334	749	1,311
Recorded Investment With Allowance	5,632	4,621	2,119
Related Allowance	4,094	2,533	610
Commercial [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	4,345	4,094	3,296
Total Recorded Investment	20,915	19,130	18,834
Commercial [Member] | C&I [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	8,439	6,627	3,906
Total Recorded Investment	26,810	24,391	22,143
Commercial [Member] | C&I [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	334	749	1,311
Recorded Investment With Allowance	5,632	4,621	2,119
Related Allowance	4,094	2,533	610
Commercial [Member] | C&I [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	4,345	4,094	3,296
Total Recorded Investment	20,844	19,021	18,713
Commercial [Member] | Municipal [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	0
Total Recorded Investment	71	109	121
Commercial [Member] | Municipal [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	0
Recorded Investment With Allowance	0
Related Allowance	0
Commercial [Member] | Municipal [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	0
Total Recorded Investment	71	109	121
Agriculture [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	350	1,445	2,149
Total Recorded Investment	750	5,398	7,893
Agriculture [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	116	3,026	328
Recorded Investment With Allowance	222	1,894	621
Related Allowance	103	1,086	184
Agriculture [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	247	359	1,965
Total Recorded Investment	412	478	6,944
Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	6,662	9,793	10,289
Total Recorded Investment	113,906	129,157	133,411
Real Estate [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	12,978	16,180	14,252
Recorded Investment With Allowance	4,680	4,629	5,894
Related Allowance	617	564	762
Real Estate [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	6,045	9,229	9,527
Total Recorded Investment	96,248	108,348	113,265
Real Estate [Member] | Construction & Development [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	591	225	164
Total Recorded Investment	7,157	5,473	6,327
Real Estate [Member] | Construction & Development [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	919	102	1,225
Recorded Investment With Allowance	777	606	230
Related Allowance	207	90	6
Real Estate [Member] | Construction & Development [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	384	135	158
Total Recorded Investment	5,461	4,765	4,872
Real Estate [Member] | Farm [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	41	2	6
Total Recorded Investment	1,707	3,142	3,105
Real Estate [Member] | Farm [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	0	997	878
Recorded Investment With Allowance	91	176	87
Related Allowance	2		0
Real Estate [Member] | Farm [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	39	2	6
Total Recorded Investment	1,616	1,969	2,140
Real Estate [Member] | Non-Owner Occupied CRE [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	2,329	4,059	3,975
Total Recorded Investment	35,365	34,468	36,158
Real Estate [Member] | Non-Owner Occupied CRE [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	2,230	2,543	2,629
Recorded Investment With Allowance	176	128	147
Related Allowance	12	15	16
Real Estate [Member] | Non-Owner Occupied CRE [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	2,317	4,044	3,959
Total Recorded Investment	32,959	31,797	33,382
Real Estate [Member] | Owner Occupied CRE [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	2,061	3,481	3,481
Total Recorded Investment	36,839	48,504	49,332
Real Estate [Member] | Owner Occupied CRE [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	5,700	6,548	5,886
Recorded Investment With Allowance	1,003	1,349	665
Related Allowance	103	152	99
Real Estate [Member] | Owner Occupied CRE [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,958	3,329	3,382
Total Recorded Investment	30,136	40,607	42,781
Real Estate [Member] | Residential [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,640	2,026	2,663
Total Recorded Investment	32,838	37,570	38,489
Real Estate [Member] | Residential [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	4,129	5,990	3,634
Recorded Investment With Allowance	2,633	2,370	4,765
Related Allowance	293	307	641
Real Estate [Member] | Residential [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,347	1,719	2,022
Total Recorded Investment	26,076	29,210	30,090
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	4	5	6
Total Recorded Investment	2,180	2,130	2,203
Consumer [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	0
Recorded Investment With Allowance	623	553	685
Related Allowance	1	1	2
Consumer [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	3	4	4
Total Recorded Investment	1,557	1,577	1,518
Consumer [Member] | Auto [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	3	4	4
Total Recorded Investment	1,692	1,675	1,770
Consumer [Member] | Auto [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	0
Recorded Investment With Allowance	596	514	589
Related Allowance	1	1	2
Consumer [Member] | Auto [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	2	3	2
Total Recorded Investment	1,096	1,161	1,181
Consumer [Member] | Non-Auto [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1	1	2
Total Recorded Investment	488	455	433
Consumer [Member] | Non-Auto [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	0
Recorded Investment With Allowance	27	39	96
Related Allowance	0
Consumer [Member] | Non-Auto [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1	1	2
Total Recorded Investment	$ 461	$ 416	$ 337