LOANS RECEIVABLE, NET - Summary of past due loans in non-accrual and past 90 days still on accrual (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Nonaccrual	$ 10,482	$ 11,983
Loans Past Due 90 Days and Still Accruing	0	116
Residential Portfolio Segment | Residential one-to-four family
Financing Receivable, Past Due [Line Items]
Nonaccrual	9,478	10,805
Loans Past Due 90 Days and Still Accruing	0	0
Residential Portfolio Segment | Multifamily
Financing Receivable, Past Due [Line Items]
Nonaccrual	135	139
Loans Past Due 90 Days and Still Accruing	0	0
Nonresidential Portfolio Segment | Non-residential
Financing Receivable, Past Due [Line Items]
Nonaccrual	686	857
Loans Past Due 90 Days and Still Accruing	0	0
Construction and Land Portfolio Segment | Construction
Financing Receivable, Past Due [Line Items]
Nonaccrual	0	0
Loans Past Due 90 Days and Still Accruing	0	0
Commercial Portfolio Segment | Commercial and industrial (including PPP)
Financing Receivable, Past Due [Line Items]
Nonaccrual	2	0
Loans Past Due 90 Days and Still Accruing	0	116
Junior Lien Portfolio Segment | Junior liens
Financing Receivable, Past Due [Line Items]
Nonaccrual	181	182
Loans Past Due 90 Days and Still Accruing	$ 0	$ 0