LOANS RECEIVABLE AND ALLOWANCE FOR CREDIT LOSSES - Troubled debt restructured loans (Details) $ in Thousands	Mar. 31, 2024 USD ($) borrower loan	Dec. 31, 2023 USD ($)
Financing Receivable, Impaired [Line Items]
Restructured loans to borrowers with financial difficulty	$ 29	$ 30
Non-accrual and 90+ days past due and still accruing loans to average loans	0.21%	0.25%
Allowance for credit losses to non-accrual and 90 days or more and still accruing loans	549.10%	409.30%
Single-family Residential
Financing Receivable, Impaired [Line Items]
Number of loans | borrower	1
Troubled debt restructured loans	$ 29,000
Real Estate Loan | Single-family Residential
Financing Receivable, Impaired [Line Items]
Restructured loans to borrowers with financial difficulty	$ 29	$ 30
Number of loans | loan	1