LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES - Allowance for credit losses (Details) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020 USD ($) borrower	Sep. 30, 2019 USD ($) borrower	Dec. 31, 2019 USD ($)
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Average loans	$ 281,773	$ 293,958
Net charge-offs to average loans (annualized)	0.07%	0.14%
Number of borrowers \| borrower	30	47
Loans charged off	$ 277	$ 519	$ 616
Outstanding commitments	33,100	34,600
Unfunded commitments
Beginning balance	37	35	35
Reduction of unfunded reserve	(8)	(23)
Provisions charged to operations		25
Ending balance	$ 29	$ 37	$ 37

Amount of writeoff of financing receivable, charged against allowance for credit loss.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448

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