Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Loans - Summary of Major Classifications of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 331,598	$ 312,370
Net deferred loan costs	178	304
Allowance for loan losses	(2,703)	(2,000)	$ (3,262)
Loans, net	329,073	310,674
Commercial [Member] \| Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	189,291	178,882
Commercial [Member] \| Land [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	1,492	1,623
Commercial [Member] \| Other Commercial Loan [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	46,184	34,072
Residential Real Estate [Member] \| First Mortgage [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	68,968	65,450
Residential Real Estate [Member] \| Construction Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	2,954	2,041
Consumer [Member] \| Other Consumer Loan [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	361	611
Consumer [Member] \| Home Equity Lines Of Credit [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 22,348	$ 29,691