Loans - Schedule of Analysis of Past due Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	$ 771	$ 1,937
Current Loans	331,144	310,433
Total Loans	331,915	312,370
Commercial Real Estate [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due		180
Current Loans	183,377	178,702
Total Loans	183,377	178,882
Commercial Land Development [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Current Loans	1,524	1,623
Total Loans	1,524	1,623
Commercial Other [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due		148
Current Loans	59,793	33,924
Total Loans	59,793	34,072
Residential Real Estate First Mortgages [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	715	1,596
Current Loans	58,741	63,854
Total Loans	59,456	65,450
Residential Real Estate Construction [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Current Loans	2,965	2,041
Total Loans	2,965	2,041
Consumer Home Equity and Lines of Credit [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	56	13
Current Loans	24,323	29,678
Total Loans	24,379	29,691
Consumer Other [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Current Loans	421	611
Total Loans	421	611
Loans Past Due 30-89 Days [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	692	1,220
Loans Past Due 30-89 Days [Member] | Commercial Other [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due		148
Loans Past Due 30-89 Days [Member] | Residential Real Estate First Mortgages [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	664	1,059
Loans Past Due 30-89 Days [Member] | Consumer Home Equity and Lines of Credit [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	28	13
Loans Past Due 90+ Days [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	79	717
Loans Past Due 90+ Days [Member] | Commercial Real Estate [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due		180
Loans Past Due 90+ Days [Member] | Residential Real Estate First Mortgages [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	51	$ 537
Loans Past Due 90+ Days [Member] | Consumer Home Equity and Lines of Credit [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	$ 28