Loans - Summary of Information Regarding Impaired Loans (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 5	$ 67
Recorded Investment	12,073	8,041
Unpaid Principal	6	68
Principal Balance	12,364	8,405
Reserve	5	67
Average Investment	53	59
Average Investment	9,106	3,582
Interest Recognized	0	0
Interest Recognized	637	128
Recorded Investment	12,068	7,974
Principal Balance	12,358	8,337
Related Allowance	5	67
Average Investment	9,053	3,523
Interest Recognized	637	128
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	6,352	5,840
Principal Balance	6,352	5,840
Average Investment	6,257	1,824
Interest Recognized	275	87
Commercial Land Development [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal	1,525
Recorded Investment	1,525
Average Investment	169	126
Interest Recognized	17
Commercial Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,652	1,091
Principal Balance	3,789	1,091
Average Investment	1,983	488
Interest Recognized	89	23
Residential real estate and consumer First mortgage [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	62
Unpaid Principal	0	62
Reserve	0	62
Average Investment	48	43
Interest Recognized	0	0
Recorded Investment	517	1,016
Principal Balance	641	1,350
Average Investment	620	1,056
Interest Recognized	254	18
Consumer Home Equity and Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	5	5
Unpaid Principal	6	6
Reserve	5	5
Average Investment	5	16
Recorded Investment	22	27
Principal Balance	51	56
Average Investment	24	$ 29
Interest Recognized	$ 2

Impaired financing receivable with no related allowance.

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- Definition

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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)
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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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

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Amount of allowance for credit losses related to recorded investment.

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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