COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	9 Months Ended
	May 31, 2018	Aug. 31, 2014	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019
Contingencies And Commitments [Line Items]
Accrued incentives (fund level)					$ 828,929	$ 864,900
Compensation expense related to accrued incentives (fund level)					447,038	462,684
Contingent consideration income (expense)			$ 2,200	$ 2,100
Capital commitments					344,300	237,300
Oaktree Opportunities Fund XI, L.P.
Contingencies And Commitments [Line Items]
Capital commitments					712,500
Highstar Capital
Contingencies And Commitments [Line Items]
Contingent consideration	$ 36,100	$ 60,000
Period of performance		7 years
Reduction in contingent consideration	$ 7,100
Contingent consideration, fair value			$ 4,500	$ 4,500
Consolidated Funds
Contingencies And Commitments [Line Items]
Aggregate potential credit and investment commitments					$ 600	$ 2,300