Loans - Schedule of Analysis of Past due Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	$ 968	$ 2,094
Current Loans	342,256	370,495
Total Loans	343,224	372,589
Commercial Real Estate [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Current Loans	190,173	191,645
Total Loans	190,173	191,645
Commercial Land Development [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	0	303
Current Loans	1,851	1,884
Total Loans	1,851	2,187
Commercial Other [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Current Loans	38,546	30,508
Total Loans	38,546	30,508
Residential Real Estate First Mortgages [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	890	1,561
Current Loans	72,316	106,523
Total Loans	73,206	108,084
Residential Real Estate Construction [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Current Loans	3,669	2,097
Total Loans	3,669	2,097
Consumer Home Equity and Lines of Credit [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	77	228
Current Loans	33,939	35,926
Total Loans	34,016	36,154
Consumer Other [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	1	2
Current Loans	1,762	1,912
Total Loans	1,763	1,914
Loans Past Due 30-89 Days [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	442	1,687
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	399	1,470
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	42	215
Loans Past Due 30-89 Days [Member] | Consumer Other [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	1	2
Loans Past Due 90+ Days [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	526	407
Loans Past Due 90+ Days [Member] | Commercial Land Development [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	0	303
Loans Past Due 90+ Days [Member] | Residential Real Estate First Mortgages [Member]
Loans, Notes and Certificates, and Loan Servicing Rights [Line Items]
Past Due	491	91
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	$ 35	$ 13