BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and cash equivalents	$ 32,111	$ 13,292	$ 32,111	$ 13,292	$ 23,801
Other assets	9,301		9,301		$ 9,222
Decrease to net cash provided by (used in) operating activities			(7,169)	(32,563)
Asset management and other fees to related parties	(2,387)	(2,699)	(7,408)	(10,496)
Non-segment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expense reimbursements to related parties	639	630	2,066	1,819
Reportable segments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expense reimbursements to related parties	$ 901	652	$ 2,581	1,840
Revision of Prior Period, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and cash equivalents		(1,308)		(1,308)		$ (272)
Other assets		1,308		1,308		$ 272
Decrease to net cash provided by (used in) operating activities				1,036
Revision of Prior Period, Adjustment | Reclassification, Type, One
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Asset management and other fees to related parties		630		1,819
Revision of Prior Period, Adjustment | Reclassification, Type, Two
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Asset management and other fees to related parties		652		1,840
Revision of Prior Period, Adjustment | Non-segment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expense reimbursements to related parties		630		1,819
Revision of Prior Period, Adjustment | Reportable segments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expense reimbursements to related parties		$ 652		$ 1,840