FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value of Financial Instruments Not Recorded at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Carrying Amount
Liabilities:
Mortgage payable	$ 163,700	$ 163,700
Junior subordinated notes	27,070	27,070
Carrying Amount | SBA 7(a) loans receivable, subject to credit risk
Assets:
Loans receivable	15,435	10,539
Carrying Amount | SBA 7(a) loans receivable, subject to loan-backed notes
Assets:
Loans receivable	36,913	43,263
Carrying Amount | SBA 7(a) loans receivable, subject to secured borrowings
Assets:
Loans receivable	1,832	3,105
Carrying Amount | SBA 7(a) loans receivable, held for sale
Assets:
Loans receivable	1,562	98
Estimated Fair Value | Fair Value, Measurements, Nonrecurring | Level 3
Liabilities:
Mortgage payable	160,545	158,529
Junior subordinated notes	24,839	24,667
Estimated Fair Value | Fair Value, Measurements, Nonrecurring | Level 3 | SBA 7(a) loans receivable, subject to credit risk
Assets:
Loans receivable	15,400	10,482
Estimated Fair Value | Fair Value, Measurements, Nonrecurring | Level 3 | SBA 7(a) loans receivable, subject to loan-backed notes
Assets:
Loans receivable	39,815	46,701
Estimated Fair Value | Fair Value, Measurements, Nonrecurring | Level 3 | SBA 7(a) loans receivable, subject to secured borrowings
Assets:
Loans receivable	1,832	3,105
Estimated Fair Value | Fair Value, Measurements, Nonrecurring | Level 3 | SBA 7(a) loans receivable, held for sale
Assets:
Loans receivable	$ 1,699	$ 82