Fair Values of Assets and Liabilities - Fair Value Measurements, Recurring and Nonrecurring (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financial Assets:
Cash and due from banks	$ 30,625	$ 4,009
Interest-bearing time deposits with other banks	2,488	2,735
Federal Home Loan Bank stock	2,776	2,971
Bank-owned life insurance	4,292	4,267
Loans, net	378,335	341,980
Accrued interest receivable	1,360	1,235
Financial Liabilities:
Total deposits	330,625	281,616
Advances from Federal Home Loan Bank	51,312	66,219
Advances from Federal Reserve Bank	25,713
Mortgagors’ tax escrow	706	586
Cash And Due From Banks
Other assets:
Assets, Fair Value Disclosure	30,625	4,009
Interest-bearing time deposits with other banks [Member]
Other assets:
Assets, Fair Value Disclosure	2,488	2,735
Federal Home Loan Bank stock [Member]
Other assets:
Assets, Fair Value Disclosure	2,776	2,971
Bank Owned Life Insurance
Other assets:
Assets, Fair Value Disclosure	4,292	4,267
Loans, net [Member]
Other assets:
Assets, Fair Value Disclosure	377,325	336,847
Accrued Interest Receivable
Other assets:
Assets, Fair Value Disclosure	1,360	1,235
Deposits
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	331,080	281,707
Federal Home Loan Bank Borrowings [Member]
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	52,897	66,060
Federal Reserve Bank Advances [Member]
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	25,713
Mortgagors' tax escrow [Member]
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	706	586
Fair Value, Inputs, Level 1 [Member] | Cash And Due From Banks
Other assets:
Assets, Fair Value Disclosure	30,625	4,009
Fair Value, Inputs, Level 1 [Member] | Accrued Interest Receivable
Other assets:
Assets, Fair Value Disclosure	1,360	1,235
Fair Value, Inputs, Level 1 [Member] | Deposits
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	272,576	220,596
Fair Value, Inputs, Level 2 [Member] | Interest-bearing time deposits with other banks [Member]
Other assets:
Assets, Fair Value Disclosure	2,488	2,735
Fair Value, Inputs, Level 2 [Member] | Federal Home Loan Bank stock [Member]
Other assets:
Assets, Fair Value Disclosure	2,776	2,971
Fair Value, Inputs, Level 2 [Member] | Bank Owned Life Insurance
Other assets:
Assets, Fair Value Disclosure	4,292	4,267
Fair Value, Inputs, Level 2 [Member] | Deposits
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	58,504	61,111
Fair Value, Inputs, Level 2 [Member] | Federal Home Loan Bank Borrowings [Member]
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	52,897	66,060
Fair Value, Inputs, Level 2 [Member] | Federal Reserve Bank Advances [Member]
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	25,713
Fair Value, Inputs, Level 2 [Member] | Mortgagors' tax escrow [Member]
Financial Liabilities:
Financial Liabilities Fair Value Disclosure	706	586
Fair Value, Inputs, Level 3 [Member] | Loans, net [Member]
Other assets:
Assets, Fair Value Disclosure	$ 377,325	$ 336,847