Loans - Average Recorded Investment of Impaired Loans by Class of Loan (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan Losses Allocated
Average Recorded Investment, With no allowance recorded	$ 2,857	$ 2,301	$ 4,597
Average Recorded Investment, With an allowance recorded	4,646	993	2,502
Average Recorded Investment	7,503	3,294	7,099
Construction and Land Development
Allowance for Loan Losses Allocated
Average Recorded Investment, With no allowance recorded	301	378	921
Average Recorded Investment, With an allowance recorded	147	0	0
Commercial Real Estate
Allowance for Loan Losses Allocated
Average Recorded Investment, With no allowance recorded	13
Commercial Real Estate \| Nonfarm, nonresidential
Allowance for Loan Losses Allocated
Average Recorded Investment, With no allowance recorded		0	1,796
Average Recorded Investment, With an allowance recorded	40	0	0
Residential Real Estate
Allowance for Loan Losses Allocated
Average Recorded Investment, With an allowance recorded	56
Residential Real Estate \| Closed-end 1-4 family
Allowance for Loan Losses Allocated
Average Recorded Investment, With no allowance recorded	587	715	649
Average Recorded Investment, With an allowance recorded		0	22
Residential Real Estate \| Other
Allowance for Loan Losses Allocated
Average Recorded Investment, With no allowance recorded	1,286	553	331
Commercial and Industrial
Allowance for Loan Losses Allocated
Average Recorded Investment, With no allowance recorded	670	655	899
Average Recorded Investment, With an allowance recorded	4,403	993	2,480
Consumer and Other
Allowance for Loan Losses Allocated
Average Recorded Investment, With no allowance recorded	$ 0	$ 0	$ 1

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

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Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

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-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

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