Loans Held for Investment and Allowance for Loan Losses - Schedule of Loans Modified and Considered Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021 USD ($) SecurityLoan	Jun. 30, 2020 USD ($) SecurityLoan	Jun. 30, 2021 USD ($) SecurityLoan	Jun. 30, 2020 USD ($) SecurityLoan
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	8	5	13	12
Pre-Modification Recorded Investment	$ 1,304	$ 319	$ 2,150	$ 755
Post-Modification Recorded Investment	$ 1,304	$ 319	$ 2,150	$ 755
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	2	4	4	9
Pre-Modification Recorded Investment	$ 212	$ 196	$ 361	$ 484
Post-Modification Recorded Investment	$ 212	$ 196	$ 361	$ 484
Commercial [Member] \| Commercial – C&I [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	2		4
Pre-Modification Recorded Investment	$ 212		$ 361
Post-Modification Recorded Investment	$ 212		$ 361
Agriculture [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	1		1	1
Pre-Modification Recorded Investment	$ 68		$ 68	$ 134
Post-Modification Recorded Investment	$ 68		$ 68	$ 134
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	4	1	7	1
Pre-Modification Recorded Investment	$ 993	$ 123	$ 1,690	$ 123
Post-Modification Recorded Investment	$ 993	$ 123	$ 1,690	$ 123
Real Estate [Member] \| Construction & Development [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	1		1
Pre-Modification Recorded Investment	$ 200		$ 200
Post-Modification Recorded Investment	$ 200		$ 200
Real Estate [Member] \| Owner Occupied CRE [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	2		3
Pre-Modification Recorded Investment	$ 548		$ 1,047
Post-Modification Recorded Investment	$ 548		$ 1,047
Real Estate [Member] \| Residential [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	1		3
Pre-Modification Recorded Investment	$ 245		$ 443
Post-Modification Recorded Investment	$ 245		$ 443
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	1		1	1
Pre-Modification Recorded Investment	$ 31		$ 31	$ 14
Post-Modification Recorded Investment	$ 31		$ 31	$ 14
Consumer [Member] \| Auto [Member]
Financing Receivable, Modifications [Line Items]
Number \| SecurityLoan	1		1
Pre-Modification Recorded Investment	$ 31		$ 31
Post-Modification Recorded Investment	$ 31		$ 31

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524

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Amount, after troubled debt restructuring, of modified financing receivable.

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Amount, before troubled debt restructuring, of financing receivable to be modified.

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