BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loans Receivable (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2015	Mar. 11, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized retained loan discounts	$ 7,328,000		$ 7,328,000		$ 7,622,000
Loan receivable, nonaccrual, past due period (more than)			60 days
Loans receivable, impairment (recovery)	36,000	$ 1,000	$ (16,000)	$ (56,000)
Impaired loans receivable	0	$ 0	0	$ 0
SBA 7(a) loans receivable, subject to secured borrowings
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized acquisition discounts related to sold loans						$ 15,951,000
PMC Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Discount on acquisition							$ 33,907,000
Acquisition discount	$ 565,000		$ 565,000		$ 624,000