LOANS RECEIVABLE, NET - Summary of loans receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 1,281,310	$ 1,278,837
Deferred fees, costs and premiums and discounts, net	6,299	5,236
Allowance for loan losses	(14,425)	(16,959)	$ (14,500)
Allowance for credit loss less deferred fees, costs and discounts, net	(8,126)	(11,723)
Loans receivable, net	1,273,184	1,267,114
Residential Portfolio Segment \| Residential one-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	560,976	611,603
Allowance for loan losses	(2,822)	(3,579)	(3,446)
Residential Portfolio Segment \| Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	515,240	427,436
Allowance for loan losses	(5,263)	(5,460)	(4,256)
Non-residential \| Non-residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	141,561	128,141
Allowance for loan losses	(2,846)	(3,244)	(2,548)
Construction and land \| Construction and land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	23,419	33,691
Allowance for loan losses	(2,678)	(3,655)	(3,028)
Junior liens \| Junior liens
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	18,464	23,814
Allowance for loan losses	(636)	(916)	(1,002)
Commercial and industrial (including PPP)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	4,800	131
Commercial and industrial (including PPP) \| Commercial and industrial (including PPP)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	21,563	54,053
Allowance for loan losses	(51)	(2)	0
Commercial and industrial (including PPP) \| PPP Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	16,800	53,900
Consumer and other \| Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	87	99
Allowance for loan losses	$ (38)	$ (48)	$ (56)

Financing Receivable, Allowance For Credit Loss, Unamortized Debt Fees And Costs And Unamortized Discounts

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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