FAIR VALUE OF FINANCIAL INSTRUMENTS - Unobservable Inputs (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
SBA 7(a) loans receivable, subject to loan-backed notes | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate of prepayment	13.41%	13.41%
SBA 7(a) loans receivable, subject to loan-backed notes | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate of prepayment	16.80%	16.80%
SBA 7(a) loans receivable, subject to credit risk | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate of prepayment	9.85%	9.85%
SBA 7(a) loans receivable, subject to credit risk | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate of prepayment	17.50%	17.50%
SBA 7(a) loans receivable, subject to secured borrowings | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate of prepayment	11.77%	11.77%
SBA 7(a) loans receivable, subject to secured borrowings | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate of prepayment	16.80%	16.80%
Measurement Input, Discount Rate | Mortgages Payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for debt	0.0275
Measurement Input, Discount Rate | Mortgages Payable | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for debt		0.0367
Measurement Input, Discount Rate | Junior Subordinated Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for debt	0.0570	0.0616
Measurement Input, Discount Rate | SBA 7(a) loans receivable, subject to loan-backed notes | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for loans receivable	0.0375	0.0525
Measurement Input, Discount Rate | SBA 7(a) loans receivable, subject to loan-backed notes | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for loans receivable	0.0575	0.0725
Measurement Input, Discount Rate | SBA 7(a) loans receivable, subject to credit risk | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for loans receivable	0.0375	0.0525
Measurement Input, Discount Rate | SBA 7(a) loans receivable, subject to credit risk | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for loans receivable	0.0625	0.0775
Measurement Input, Discount Rate | SBA 7(a) loans receivable, subject to secured borrowings | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for loans receivable	0.0525	0.0675
Measurement Input, Discount Rate | SBA 7(a) loans receivable, subject to secured borrowings | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input for loans receivable	0.0600	0.0750