LOANS RECEIVABLE, NET - Credit quality indicators (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	$ 1,341,486	$ 1,287,609
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	1,329,367	1,269,218
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	416	5,213
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	11,703	13,178
Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Residential Portfolio Segment | Residential one-to-four family
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	583,524	566,483
Residential Portfolio Segment | Residential one-to-four family | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	573,394	555,184
Residential Portfolio Segment | Residential one-to-four family | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	274	0
Residential Portfolio Segment | Residential one-to-four family | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	9,856	11,299
Residential Portfolio Segment | Residential one-to-four family | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Residential Portfolio Segment | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	518,192	516,568
Residential Portfolio Segment | Multifamily | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	517,521	510,815
Residential Portfolio Segment | Multifamily | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	5,069
Residential Portfolio Segment | Multifamily | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	671	684
Residential Portfolio Segment | Multifamily | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Nonresidential Portfolio Segment | Non-residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	187,169	141,534
Nonresidential Portfolio Segment | Non-residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	186,032	140,377
Nonresidential Portfolio Segment | Non-residential | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	142	144
Nonresidential Portfolio Segment | Non-residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	995	1,013
Nonresidential Portfolio Segment | Non-residential | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Construction and Land Portfolio Segment | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	18,439	23,420
Construction and Land Portfolio Segment | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	18,439	23,420
Construction and Land Portfolio Segment | Construction | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Construction and Land Portfolio Segment | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Construction and Land Portfolio Segment | Construction | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Junior Lien Portfolio Segment | Junior liens
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	18,177	18,550
Junior Lien Portfolio Segment | Junior liens | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	17,996	18,368
Junior Lien Portfolio Segment | Junior liens | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Junior Lien Portfolio Segment | Junior liens | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	181	182
Junior Lien Portfolio Segment | Junior liens | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Commercial Portfolio Segment | Commercial and industrial (including PPP)
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	15,948	20,966
Commercial Portfolio Segment | Commercial and industrial (including PPP) | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	15,948	20,966
Commercial Portfolio Segment | Commercial and industrial (including PPP) | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Commercial Portfolio Segment | Commercial and industrial (including PPP) | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Commercial Portfolio Segment | Commercial and industrial (including PPP) | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable		0
Consumer and Other Portfolio Segment | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	37	88
Consumer and Other Portfolio Segment | Consumer and other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	37	88
Consumer and Other Portfolio Segment | Consumer and other | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Consumer and Other Portfolio Segment | Consumer and other | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Consumer and Other Portfolio Segment | Consumer and other | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	$ 0	$ 0