SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Consolidated and Non-Consolidated Variable Interest Entities Narrative) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) subsidiary	Dec. 31, 2019 USD ($) subsidiary
Variable Interest Entity [Line Items]
Percent of voting power in Medley LLC	100.00%
Total assets of consolidated variable interest entity	$ 38,711	$ 48,796
Total liabilities of consolidated variable interest entity, less than	170,691	167,629
Fair value of investments in non-consolidated VIEs	2,400	3,000
Receivables included as a component of other assets and clawback obligation	600	1,300
Accrued clawback obligations	7,200	7,200
Maximum loss exposure	3,000
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total assets of consolidated variable interest entity	900	1,200
Total liabilities of consolidated variable interest entity, less than	$ 100	$ 100
Medley LLC
Variable Interest Entity [Line Items]
Number of majority owned subsidiaries | subsidiary	4	7
Medley LLC
Variable Interest Entity [Line Items]
Parent ownership percentage of LLC	20.20%	19.30%
Noncontrolling interest ownership percentage of LLC	79.80%	80.70%