LOANS RECEIVABLE - Summary of loans receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 1,547,384		$ 1,560,730
Less: Allowance for credit losses	13,027	$ 13,749	14,154	$ 14,413	$ 14,153	$ 13,400
Loans receivable, net	1,534,357		1,546,576
Residential Portfolio Segment | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	526,453		550,929
Less: Allowance for credit losses	1,825	1,919	1,968	1,994	2,056	2,264
Residential Portfolio Segment | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	671,185		682,564
Less: Allowance for credit losses	6,677	7,003	7,046	7,017	7,191	5,491
Commercial Real Estate Portfolio Segment | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total			232,505
Commercial Real Estate Portfolio Segment | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	241,867		232,505
Less: Allowance for credit losses	3,696	3,231	3,748	3,813	3,570	3,357
Construction and Land Portfolio Segment | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	71,882		60,414
Less: Allowance for credit losses	636	884	1,222	1,428	1,190	1,697
Junior Lien Portfolio Segment | Junior liens
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	23,653		22,503
Less: Allowance for credit losses	84	77	76	50	46	451
Commercial Portfolio Segment | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	12,261		11,768
Less: Allowance for credit losses	108	635	94	111	100	47
Consumer and Other Portfolio Segment | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	83		47
Less: Allowance for credit losses	$ 1	$ 0	$ 0	$ 0	$ 0	$ 0