Loans Held for Investment and Allowance for Loan Losses - Schedule of loans that are individually evaluated for credit losses (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Financing Receivable, Impaired [Line Items]
Related Allowance	$ 18,744	$ 17,870	$ 18,573
Total Recorded Investment	152,160	161,185	190,416
Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	17,257	19,955	21,964
Recorded Investment With Allowance	11,466	11,697	17,369
Related Allowance	3,928	4,184	2,952
Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	14,816	13,686	15,621
Total Recorded Investment	123,437	129,533	151,083
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	7,793	6,627	5,417
Total Recorded Investment	25,427	24,500	29,066
Commercial [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	95	749	1,806
Recorded Investment With Allowance	4,616	4,621	2,903
Related Allowance	2,525	2,533	777
Commercial [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	5,268	4,094	4,640
Total Recorded Investment	20,716	19,130	24,357
Commercial [Member] | C&I [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	7,793	6,627	3,881
Total Recorded Investment	25,331	24,391	19,289
Commercial [Member] | C&I [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	95	749	1,806
Recorded Investment With Allowance	4,616	4,621	2,903
Related Allowance	2,525	2,533	777
Commercial [Member] | C&I [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	5,268	4,094	3,104
Total Recorded Investment	20,620	19,021	14,580
Commercial [Member] | Municipal [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance			1,536
Total Recorded Investment	96	109	9,777
Commercial [Member] | Municipal [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance			1,536
Total Recorded Investment	96	109	9,777
Agriculture [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,222	1,445	1,790
Total Recorded Investment	4,749	5,398	6,859
Agriculture [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	2,349	3,026	457
Recorded Investment With Allowance	1,989	1,894	612
Related Allowance	946	1,086	170
Agriculture [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	276	359	1,620
Total Recorded Investment	411	478	5,790
Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	9,725	9,793	11,359
Total Recorded Investment	120,100	129,157	152,324
Real Estate [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	14,813	16,180	19,701
Recorded Investment With Allowance	4,419	4,629	13,462
Related Allowance	456	564	2,004
Real Estate [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	9,269	9,229	9,355
Total Recorded Investment	100,868	108,348	119,161
Real Estate [Member] | Construction & Development [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,490	225	880
Total Recorded Investment	10,226	5,473	12,497
Real Estate [Member] | Construction & Development [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance		102	1,124
Recorded Investment With Allowance	594	606	171
Related Allowance	44	90	12
Real Estate [Member] | Construction & Development [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,446	135	868
Total Recorded Investment	9,632	4,765	11,202
Real Estate [Member] | Farm [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance		2	671
Total Recorded Investment	2,423	3,142	10,295
Real Estate [Member] | Farm [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	1,209	997	2,241
Recorded Investment With Allowance		176	4,618
Related Allowance			590
Real Estate [Member] | Farm [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance		2	81
Total Recorded Investment	1,214	1,969	3,436
Real Estate [Member] | Non-Owner Occupied CRE [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	3,016	4,059	3,335
Total Recorded Investment	35,279	34,468	39,387
Real Estate [Member] | Non-Owner Occupied CRE [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	2,463	2,543	6,045
Recorded Investment With Allowance	111	128	1,043
Related Allowance	10	15	226
Real Estate [Member] | Non-Owner Occupied CRE [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	3,006	4,044	3,109
Total Recorded Investment	32,705	31,797	32,299
Real Estate [Member] | Owner Occupied CRE [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	3,245	3,481	3,599
Total Recorded Investment	36,896	48,504	55,450
Real Estate [Member] | Owner Occupied CRE [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	6,187	6,548	6,081
Recorded Investment With Allowance	1,101	1,349	3,476
Related Allowance	96	152	599
Real Estate [Member] | Owner Occupied CRE [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	3,149	3,329	3,000
Total Recorded Investment	29,608	40,607	45,893
Real Estate [Member] | Residential [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,974	2,026	2,874
Total Recorded Investment	35,276	37,570	34,695
Real Estate [Member] | Residential [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	4,954	5,990	4,210
Recorded Investment With Allowance	2,613	2,370	4,154
Related Allowance	306	307	577
Real Estate [Member] | Residential [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,668	1,719	2,297
Total Recorded Investment	27,709	29,210	26,331
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	4	5	7
Total Recorded Investment	1,884	2,130	2,167
Consumer [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With Allowance	442	553	392
Related Allowance	1	1	1
Consumer [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	3	4	6
Total Recorded Investment	1,442	1,577	1,775
Consumer [Member] | Auto [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	3	4	5
Total Recorded Investment	1,494	1,675	1,716
Consumer [Member] | Auto [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With Allowance	402	514	317
Related Allowance	1	1	1
Consumer [Member] | Auto [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	2	3	4
Total Recorded Investment	1,092	1,161	1,399
Consumer [Member] | Non-Auto [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1	1	2
Total Recorded Investment	390	455	451
Consumer [Member] | Non-Auto [Member] | Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With Allowance	40	39	75
Related Allowance	0
Consumer [Member] | Non-Auto [Member] | Uncollateralized [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1	1	2
Total Recorded Investment	$ 350	$ 416	$ 376