FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value Measurement Inputs (Details) - Valuation Technique, Discounted Cash Flow	Mar. 31, 2021	Dec. 31, 2020
SBA 7(a) loans receivable, paycheck protection program | Measurement Input, Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0100	0.0100
Minimum | SBA 7(a) loans receivable, subject to credit risk | Measurement Input, Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0650	0.0650
Minimum | SBA 7(a) loans receivable, subject to credit risk | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0400	0.0400
Minimum | SBA 7(a) loans receivable, subject to loan-backed notes | Measurement Input, Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0550	0.0550
Minimum | SBA 7(a) loans receivable, subject to loan-backed notes | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0488	0.0488
Minimum | SBA 7(a) loans receivable, subject to secured borrowings | Measurement Input, Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0700	0.0700
Minimum | SBA 7(a) loans receivable, subject to secured borrowings | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0500	0.0500
Maximum | SBA 7(a) loans receivable, subject to credit risk | Measurement Input, Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0825	0.0825
Maximum | SBA 7(a) loans receivable, subject to credit risk | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.1750	0.1750
Maximum | SBA 7(a) loans receivable, subject to loan-backed notes | Measurement Input, Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0800	0.0800
Maximum | SBA 7(a) loans receivable, subject to loan-backed notes | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.1750	0.1750
Maximum | SBA 7(a) loans receivable, subject to secured borrowings | Measurement Input, Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.0775	0.0775
Maximum | SBA 7(a) loans receivable, subject to secured borrowings | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input for loans receivable	0.1750	0.1750