Loans - Summary of Information Regarding Impaired Loans (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 31	$ 97
Recorded Investment	3,726	2,377
Unpaid Principal	31	97
Principal Balance	4,099	2,693
Reserve	31	12
Average Investment	17	278
Average Investment	2,174	2,552
Interest Recognized		3
Interest Recognized	43	70
Recorded Investment	3,695	2,280
Principal Balance	4,068	2,596
Related Allowance	31	12
Average Investment	2,157	2,274
Interest Recognized	43	67
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,355	701
Principal Balance	1,355	701
Average Investment	574	658
Interest Recognized	20	40
Commercial Land Development [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		303
Principal Balance		303
Average Investment	168	303
Commercial Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,142	161
Principal Balance	1,159	161
Average Investment	319	46
Interest Recognized	10	2
Residential real estate and consumer First mortgage [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		91
Unpaid Principal		91
Reserve		6
Average Investment		154
Interest Recognized		3
Recorded Investment	1,170	1,085
Principal Balance	1,498	1,375
Average Investment	1,067	1,235
Interest Recognized	13	25
Consumer Home Equity and Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	31	6
Unpaid Principal	31	6
Reserve	31	6
Average Investment	17	124
Recorded Investment	28	30
Principal Balance	56	56
Average Investment	$ 29	$ 32

Impaired financing receivable with no related allowance.

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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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
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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 allowance for credit losses related to recorded investment.

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