SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Seed Investments and Deconsolidation of Consolidated Fund) (Details) - USD ($) $ in Thousands					9 Months Ended
	Apr. 06, 2020	Mar. 25, 2020	Oct. 28, 2019	Jun. 06, 2017	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019	Jun. 30, 2017
Assets
Cash and cash equivalents						$ 6,048	$ 10,558
Investments, at fair value						9,637	13,287
Other assets						12,021	10,283
Total Assets						38,711	48,796
Liabilities and Equity
Accounts payable, accrued expenses and other liabilities						27,080	22,835
Equity						(8,132)	(9,119)
Total Liabilities, Redeemable Non-controlling Interests and Equity						$ 38,711	48,796
STRF
Schedule of Equity Method Investments [Line Items]
Amount funded								$ 2,100
Assets
Cash and cash equivalents	$ 471						682
Investments, at fair value	1,016						1,441
Other assets	76						29
Total Assets	1,563						2,152
Liabilities and Equity
Accounts payable, accrued expenses and other liabilities	39						342
Equity	1,524						1,810
Total Liabilities, Redeemable Non-controlling Interests and Equity	1,563						2,152
Other assets eliminated							200
Equity eliminated							$ 1,800
STRF | Master Investment Agreement with DB MED Investor I LLC and DB MED Investor II LLC
Schedule of Equity Method Investments [Line Items]
Amount funded				$ 2,000	$ 2,000
Medley and ''Investors'' | Master Investment Agreement with DB MED Investor I LLC and DB MED Investor II LLC
Liabilities and Equity
Contributions to the joint venture				$ 53,800	$ 53,800
Medley and ''Investors'' | Master Investment Agreement with DB MED Investor I LLC and DB MED Investor II LLC | MCC
Liabilities and Equity
Contributions to the joint venture	$ 200	$ 100	$ 100