LOANS RECEIVABLE, NET - Aging analysis (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	$ 1,341,486	$ 1,287,609
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	2,406	1,747
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	278	567
90 Days and Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	7,617	9,615
Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	10,301	11,929
Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,331,185	1,275,680
Residential Portfolio Segment | Residential one-to-four family
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	583,524	566,483
Residential Portfolio Segment | Residential one-to-four family | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	2,147	1,736
Residential Portfolio Segment | Residential one-to-four family | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	278	457
Residential Portfolio Segment | Residential one-to-four family | 90 Days and Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	7,344	8,936
Residential Portfolio Segment | Residential one-to-four family | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	9,769	11,129
Residential Portfolio Segment | Residential one-to-four family | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	573,755	555,354
Residential Portfolio Segment | Multifamily
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	518,192	516,568
Residential Portfolio Segment | Multifamily | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Residential Portfolio Segment | Multifamily | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Residential Portfolio Segment | Multifamily | 90 Days and Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	217	0
Residential Portfolio Segment | Multifamily | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	217	0
Residential Portfolio Segment | Multifamily | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	517,975	516,568
Nonresidential Portfolio Segment | Non-residential
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	187,169	141,534
Nonresidential Portfolio Segment | Non-residential | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	222	0
Nonresidential Portfolio Segment | Non-residential | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Nonresidential Portfolio Segment | Non-residential | 90 Days and Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	381
Nonresidential Portfolio Segment | Non-residential | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	222	381
Nonresidential Portfolio Segment | Non-residential | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	186,947	141,153
Construction and Land Portfolio Segment | Construction
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	18,439	23,420
Construction and Land Portfolio Segment | Construction | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Construction and Land Portfolio Segment | Construction | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Construction and Land Portfolio Segment | Construction | 90 Days and Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Construction and Land Portfolio Segment | Construction | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Construction and Land Portfolio Segment | Construction | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	18,439	23,420
Junior Lien Portfolio Segment | Junior liens
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	18,177	18,550
Junior Lien Portfolio Segment | Junior liens | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	37	0
Junior Lien Portfolio Segment | Junior liens | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	53
Junior Lien Portfolio Segment | Junior liens | 90 Days and Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	54	182
Junior Lien Portfolio Segment | Junior liens | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	91	235
Junior Lien Portfolio Segment | Junior liens | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	18,086	18,315
Commercial Portfolio Segment | Commercial and industrial (including PPP)
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	15,948	20,966
Commercial Portfolio Segment | Commercial and industrial (including PPP) | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	11
Commercial Portfolio Segment | Commercial and industrial (including PPP) | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	57
Commercial Portfolio Segment | Commercial and industrial (including PPP) | 90 Days and Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	2	116
Commercial Portfolio Segment | Commercial and industrial (including PPP) | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	2	184
Commercial Portfolio Segment | Commercial and industrial (including PPP) | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	15,946	20,782
Consumer and Other Portfolio Segment | Consumer and other
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	37	88
Consumer and Other Portfolio Segment | Consumer and other | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0
Consumer and Other Portfolio Segment | Consumer and other | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Consumer and Other Portfolio Segment | Consumer and other | 90 Days and Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Consumer and Other Portfolio Segment | Consumer and other | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	0	0
Consumer and Other Portfolio Segment | Consumer and other | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	$ 37	$ 88