Loans - Summary of Information Regarding the Credit Quality Indicators for Residential Real Estate and Consumer Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	$ 343,224	$ 372,589
Credit Quality [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	112,654	148,249
Credit Quality [Member] | Residential First Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	73,206	108,084
Credit Quality [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	3,669	2,097
Credit Quality [Member] | Consumer Home Equity and Lines of Credit [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	34,016	36,154
Credit Quality [Member] | Consumer Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,763	1,914
Performing [Member] | Credit Quality [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	111,133	147,013
Performing [Member] | Credit Quality [Member] | Residential First Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	71,902	107,018
Performing [Member] | Credit Quality [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	3,669	2,097
Performing [Member] | Credit Quality [Member] | Consumer Home Equity and Lines of Credit [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	33,799	35,984
Performing [Member] | Credit Quality [Member] | Consumer Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,763	1,914
Non Performing [Member] | Credit Quality [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,521	1,236
Non Performing [Member] | Credit Quality [Member] | Residential First Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,304	1,066
Non Performing [Member] | Credit Quality [Member] | Consumer Home Equity and Lines of Credit [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	$ 217	$ 170