FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value of Financial Instruments Not Recorded at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Carrying Amount
Liabilities:
Mortgages payable	$ 97,100	$ 97,100
Junior subordinated notes	27,070	27,070
Carrying Amount \| SBA 7(a) loans receivable, subject to credit risk
Assets:
Loans receivable	33,552	32,509
Carrying Amount \| SBA 7(a) loans receivable, subject to loan-backed notes
Assets:
Loans receivable	22,646	23,606
Carrying Amount \| SBA 7(a) loans receivable, paycheck protection program
Assets:
Loans receivable	16,662	14,089
Carrying Amount \| SBA 7(a) loans receivable, subject to secured borrowings
Assets:
Loans receivable	8,591	8,822
Carrying Amount \| SBA 7(a) loans receivable, held for sale
Assets:
Loans receivable	2,990	4,109
Fair Value, Measurements, Nonrecurring \| Estimated Fair Value \| Level 3
Liabilities:
Mortgages payable	99,689	100,799
Junior subordinated notes	24,264	24,236
Fair Value, Measurements, Nonrecurring \| Estimated Fair Value \| Level 3 \| SBA 7(a) loans receivable, subject to credit risk
Assets:
Loans receivable	33,633	32,397
Fair Value, Measurements, Nonrecurring \| Estimated Fair Value \| Level 3 \| SBA 7(a) loans receivable, subject to loan-backed notes
Assets:
Loans receivable	23,452	24,850
Fair Value, Measurements, Nonrecurring \| Estimated Fair Value \| Level 3 \| SBA 7(a) loans receivable, paycheck protection program
Assets:
Loans receivable	17,286	14,484
Fair Value, Measurements, Nonrecurring \| Estimated Fair Value \| Level 3 \| SBA 7(a) loans receivable, subject to secured borrowings
Assets:
Loans receivable	8,681	8,914
Fair Value, Measurements, Nonrecurring \| Estimated Fair Value \| Level 3 \| SBA 7(a) loans receivable, held for sale
Assets:
Loans receivable	$ 3,373	$ 4,527

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13433-108611

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- Definition

Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

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