LOANS RECEIVABLE, NET - Credit quality indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	$ 1,287,609	$ 1,284,073
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	1,269,218	1,253,056
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	5,213	16,802
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	13,178	14,215
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	566,483	616,248
Residential Portfolio Segment | Residential one-to-four family | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	555,184	604,167
Residential Portfolio Segment | Residential one-to-four family | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Residential Portfolio Segment | Residential one-to-four family | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	11,299	12,081
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	516,568	429,095
Residential Portfolio Segment | Multifamily | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	510,815	411,369
Residential Portfolio Segment | Multifamily | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	5,069	16,648
Residential Portfolio Segment | Multifamily | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	684	1,078
Residential Portfolio Segment | Multifamily | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Non-residential | Non-residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	141,534	128,217
Non-residential | Non-residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	140,377	127,089
Non-residential | Non-residential | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	144	154
Non-residential | Non-residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	1,013	974
Non-residential | Non-residential | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Construction and land | Construction and land
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	23,420	33,630
Construction and land | Construction and land | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	23,420	33,630
Construction and land | Construction and land | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Construction and land | Construction and land | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Construction and land | Construction and land | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Junior liens | Junior liens
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	18,550	23,918
Junior liens | Junior liens | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	18,368	23,836
Junior liens | Junior liens | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Junior liens | Junior liens | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	182	82
Junior liens | Junior liens | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Commercial and industrial (including PPP) | Commercial and industrial (including PPP)
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	20,966	52,867
Commercial and industrial (including PPP) | Commercial and industrial (including PPP) | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	20,966	52,867
Commercial and industrial (including PPP) | Commercial and industrial (including PPP) | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Commercial and industrial (including PPP) | Commercial and industrial (including PPP) | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Commercial and industrial (including PPP) | Commercial and industrial (including PPP) | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable		0
Consumer and other | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	88	98
Consumer and other | Consumer and other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	88	98
Consumer and other | Consumer and other | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Consumer and other | Consumer and other | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	0	0
Consumer and other | Consumer and other | Doubtful/Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans Receivable	$ 0	$ 0