COMMITMENTS AND CONTINGENCIES - Summary of outstanding firm commitments (Detail) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Fixed Rate
Commitments and Contingencies [Line Items]
Fair value, concentration of risk, commitments	$ 8,730,200	$ 12,489,000
Fixed Rate | Residential Mortgage Loans
Commitments and Contingencies [Line Items]
Fair value, concentration of risk, commitments	8,700,200	8,524,000
Fixed Rate | Commercial Real Estate
Commitments and Contingencies [Line Items]
Fair value, concentration of risk, commitments		1,830,000
Fixed Rate | Home Equity Loans
Commitments and Contingencies [Line Items]
Fair value, concentration of risk, commitments	30,000	2,135,000
Variable Rate
Commitments and Contingencies [Line Items]
Fair value, concentration of risk, commitments	2,804,250	6,175,000
Variable Rate | Residential Mortgage Loans
Commitments and Contingencies [Line Items]
Fair value, concentration of risk, commitments		1,500,000
Variable Rate | Commercial Real Estate
Commitments and Contingencies [Line Items]
Fair value, concentration of risk, commitments	1,695,000	$ 4,675,000
Variable Rate | Home Equity Loans
Commitments and Contingencies [Line Items]
Fair value, concentration of risk, commitments	$ 1,109,250