FAIR VALUE MEASUREMENT AND FAIR VALUE OF FINANCIAL INSTRUMENTS - Balance sheet grouping (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Financial assets:
Available-for-sale, allowance for credit losses	$ 666		$ 518	$ 498		$ 498
Loans, allowance for credit losses	1,847	$ 2,001	1,915	$ 1,751	$ 1,842	$ 1,804
Carrying Amount
Financial assets:
Cash and cash equivalents	8,150		5,328
Securities available-for-sale, net of allowance for credit losses	35,116		48,635
Federal Home Loan Bank of New York stock, at cost	3,354		3,272
Federal Reserve Bank stock, at cost	270		131
Loans, net of allowance for credit losses	236,710		226,030
Accrued interest receivable	1,512		1,479
Financial liabilities:
Deposits	234,985		234,426
Federal Home Loan Bank advances	34,629		35,567
Accrued interest payable	95		120
Advances from borrowers for taxes and insurance	3,220		2,389
Fair Value
Financial assets:
Cash and cash equivalents	8,150		5,328
Securities available-for-sale, net of allowance for credit losses	35,116		48,635
Federal Home Loan Bank of New York stock, at cost	3,354		3,272
Federal Reserve Bank stock, at cost	270		131
Loans, net of allowance for credit losses	234,535		213,685
Accrued interest receivable	1,512		1,479
Financial liabilities:
Deposits	234,013		225,763
Federal Home Loan Bank advances	36,049		36,987
Accrued interest payable	95		120
Advances from borrowers for taxes and insurance	3,220		2,389
Level 1
Financial assets:
Cash and cash equivalents	8,150		5,328
Accrued interest receivable	1,512		1,479
Financial liabilities:
Deposits	84,781		85,684
Accrued interest payable	95		120
Advances from borrowers for taxes and insurance	3,220		2,389
Level 2
Financial assets:
Securities available-for-sale, net of allowance for credit losses	35,116		48,487
Federal Home Loan Bank of New York stock, at cost	3,354		3,272
Federal Reserve Bank stock, at cost	270		131
Financial liabilities:
Deposits	149,232		140,079
Federal Home Loan Bank advances	36,049		36,987
Level 3 | Carrying Amount
Financial assets:
Securities available-for-sale, net of allowance for credit losses			148
Loans, net of allowance for credit losses	$ 234,535		$ 213,685