FAIR VALUE - Financial Instruments by Fair-value Hierarchy Level (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	$ 6,890	$ 6,502
Derivative liabilities	(4,254)	(2,961)
Oaktree Capital Group Excluding Consolidated Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	34,934	74,899
Derivative assets, at fair value		4,038
Oaktree Capital Group Excluding Consolidated Funds | Foreign-currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value		1,654
Derivative liabilities	(1,703)	(2,318)
Oaktree Capital Group Excluding Consolidated Funds | Cross-currency swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value		2,384
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	44,260	625,471
Contingent consideration	0	(6,657)
Total liabilities	(1,703)	(8,975)
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, at fair value	0	1,654
Derivative liabilities	(1,703)	(2,318)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Foreign-currency forward contracts | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	(94)	(3)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Cross-currency swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0	2,384
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | U.S. Treasury securities and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	9,232	546,531
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	35,028	74,902
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	9,232	546,531
Contingent consideration	0	0
Total liabilities	0	0
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, at fair value	0	0
Derivative liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I | Cross-currency swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I | U.S. Treasury securities and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	9,232	546,531
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	4,717	33,514
Contingent consideration	0	0
Total liabilities	(1,703)	(2,318)
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, at fair value	0	1,654
Derivative liabilities	(1,703)	(2,318)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | Cross-currency swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0	2,384
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | U.S. Treasury securities 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	4,717	29,476
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	30,311	45,426
Contingent consideration	0	(6,657)
Total liabilities	0	(6,657)
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, at fair value	0	0
Derivative liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | Cross-currency swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | U.S. Treasury securities 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	$ 30,311	$ 45,426