LOANS RECEIVABLE, NET - Summary of impaired loans by class of loan (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
With no related allowance recorded:
Unpaid Principal Balance	$ 14,208	$ 13,681
Recorded Investment	14,424	13,605
Average Recorded Investment	15,630	3,315
Interest Income Recognized	314	350
Cash Basis Interest Recognized	298	339
With an allowance recorded:
Unpaid Principal Balance	1,099	1,921
Recorded Investment	1,098	1,921
Allowance for Loan Losses Allocated	68	184
Average Recorded Investment	1,284	859
Interest Income Recognized	52	65
Cash Basis Interest Recognized	48	58
Total
Unpaid Principal Balance	15,307	15,602
Recorded Investment	15,522	15,526
Allowance for Loan Losses Allocated	68	184
Average Recorded Investment	16,914	4,174
Interest Income Recognized	366	415
Cash Basis Interest Recognized	346	397
Residential Portfolio Segment \| Residential one-to-four family
With no related allowance recorded:
Unpaid Principal Balance	8,744	6,399
Recorded Investment	9,108	6,508
Average Recorded Investment	9,534	473
Interest Income Recognized	75	97
Cash Basis Interest Recognized	75	96
With an allowance recorded:
Unpaid Principal Balance	1,062	1,519
Recorded Investment	1,061	1,521
Allowance for Loan Losses Allocated	31	108
Average Recorded Investment	1,243	679
Interest Income Recognized	50	53
Cash Basis Interest Recognized	46	47
Total
Allowance for Loan Losses Allocated	31	108
Residential Portfolio Segment \| Multifamily
With no related allowance recorded:
Unpaid Principal Balance	684	1,216
Recorded Investment	684	1,226
Average Recorded Investment	1,170	405
Interest Income Recognized	26	45
Cash Basis Interest Recognized	24	41
With an allowance recorded:
Unpaid Principal Balance	0	353
Recorded Investment	0	352
Allowance for Loan Losses Allocated	0	28
Average Recorded Investment	0	157
Interest Income Recognized	0	11
Cash Basis Interest Recognized	0	10
Total
Allowance for Loan Losses Allocated	0	28
Non-residential \| Non-residential
With no related allowance recorded:
Unpaid Principal Balance	4,725	6,006
Recorded Investment	4,577	5,812
Average Recorded Investment	4,869	2,410
Interest Income Recognized	210	207
Cash Basis Interest Recognized	196	201
With an allowance recorded:
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Cash Basis Interest Recognized	0	0
Total
Allowance for Loan Losses Allocated	0	0
Construction and land \| Construction and land
With no related allowance recorded:
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Cash Basis Interest Recognized	0	0
With an allowance recorded:
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Cash Basis Interest Recognized	0	0
Total
Allowance for Loan Losses Allocated	0	0
Commercial and industrial (including PPP) \| Commercial and Industrial (including PPP)
With no related allowance recorded:
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Cash Basis Interest Recognized	0	0
With an allowance recorded:
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Cash Basis Interest Recognized	0	0
Total
Allowance for Loan Losses Allocated	0	0
Junior liens \| Junior liens
With no related allowance recorded:
Unpaid Principal Balance	55	60
Recorded Investment	55	59
Average Recorded Investment	57	27
Interest Income Recognized	3	1
Cash Basis Interest Recognized	3	1
Consumer and other \| Consumer and other
With an allowance recorded:
Unpaid Principal Balance	37	49
Recorded Investment	37	48
Allowance for Loan Losses Allocated	37	48
Average Recorded Investment	41	23
Interest Income Recognized	2	1
Cash Basis Interest Recognized	2	1
Total
Allowance for Loan Losses Allocated	$ 37	$ 48

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