FAIR VALUE MEASUREMENT AND FAIR VALUE OF FINANCIAL INSTRUMENTS - Balance sheet grouping (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Financial assets:
Available-for-sale, allowance for credit losses	$ 498		$ 498	$ 498
Loans, allowance for credit losses	1,751	$ 1,842	1,804	$ 2,052	$ 2,052	$ 2,045
Level 1 | Carrying Amount
Financial assets:
Cash and cash equivalents	12,830		6,788
Accrued interest receivable	1,370		1,247
Financial liabilities:
Deposits	228,817		210,571
Accrued interest payable	153		146
Advances from borrowers for taxes and insurance	3,008		2,349
Level 1 | Fair Value
Financial assets:
Cash and cash equivalents	12,830		6,788
Accrued interest receivable	1,370		1,247
Financial liabilities:
Deposits	209,443		187,395
Accrued interest payable	153		146
Advances from borrowers for taxes and insurance	3,008		2,349
Level 2 | Carrying Amount
Financial assets:
Securities available-for-sale, net of allowance for credit losses of $498 and $498	48,597		46,484
Federal Home Loan Bank of New York stock, at cost	3,453		3,361
Financial liabilities:
Federal Home Loan Bank advances	40,567		41,253
Level 2 | Fair Value
Financial assets:
Securities available-for-sale, net of allowance for credit losses of $498 and $498	48,597		46,484
Federal Home Loan Bank of New York stock, at cost	3,453		3,361
Financial liabilities:
Federal Home Loan Bank advances	40,567		41,253
Level 3 | Carrying Amount
Financial assets:
Loans, net of allowance for credit losses of $1,751 and $1,804	209,597		202,429
Level 3 | Fair Value
Financial assets:
Loans, net of allowance for credit losses of $1,751 and $1,804	$ 197,894		$ 189,034