FAIR VALUE - Financial Instruments by Fair-value Hierarchy Level (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 560
Derivative liabilities	(9,279)	$ (4,254)
Oaktree Capital Group Excluding Consolidated Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	19,169	34,934
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	36,593	44,260
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Foreign-currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	221	0
Derivative liabilities	(8,733)	(1,703)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Foreign-currency forward contracts | Corporate Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	137
Derivative liabilities	(8,190)	(94)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | U.S. Treasury and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	9,150	9,232
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Corporate investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	27,222	35,028
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	9,150	9,232
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I | Foreign-currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I | U.S. Treasury and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	9,150	9,232
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I | Corporate investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	4,109	4,717
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | Foreign-currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	221	0
Derivative liabilities	(8,733)	(1,703)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | U.S. Treasury and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | Corporate investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	3,888	4,717
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	23,334	30,311
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | Foreign-currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | U.S. Treasury and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | Corporate investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	$ 23,334	$ 30,311