FAIR VALUE - Financial Instruments by Fair-value Hierarchy Level (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 6,502
Contingent consideration	$ (6,700)	(6,700)
Derivative liabilities	(5,873)	(2,961)
Oaktree Capital Group Excluding Consolidated Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	73,080	74,899
Derivative assets		4,038
Derivative liabilities	(4,716)
Oaktree Capital Group Excluding Consolidated Funds | Cross-currency swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		2,384
Derivative liabilities	(2,197)
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	462,169	625,471
Total liabilities	11,453	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	1,148	1,654
Derivative liabilities	(2,519)	(2,318)
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	0	2,384
Derivative liabilities	(2,197)	0
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	387,585	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	73,436	74,902
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Contingent liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	(6,737)	(6,657)
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	387,585	546,531
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	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	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	387,585	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 I | Contingent liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	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	32,350	33,514
Total liabilities	4,716	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	1,148	1,654
Derivative liabilities	(2,519)	(2,318)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | Foreign-currency forward contracts | Corporate investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	(356)	(3)
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	0	2,384
Derivative liabilities	(2,197)	0
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	31,202	29,476
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | Contingent liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	0	0
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	42,234	45,426
Total liabilities	6,737	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	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	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	42,234	45,426
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | Contingent liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	(6,737)	(6,657)
Net (income) loss attributable to non-controlling interests in consolidated funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	6,939,504	6,531,385
Derivative assets		2,464
Net (income) loss attributable to non-controlling interests in consolidated funds | Options and futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		189
Net (income) loss attributable to non-controlling interests in consolidated funds | Level III
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	226,689	325,922
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	6,939,504	6,531,385
Derivative assets	3,350	2,464
Total assets	6,942,854	6,533,849
Derivative liabilities	(1,157)	(643)
Total liabilities	4,313,180	4,131,246
Net (income) loss attributable to non-controlling interests in 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	3,350	2,275
Derivative liabilities	(1,157)	(643)
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Options and futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	189
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Corporate debt – bank debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	5,548,077	5,352,978
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Corporate debt – all other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	1,286,001	1,149,435
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Equities – common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	46,412	27,546
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Equities – preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	1,934	1,426
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	57,080	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level I
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	3,440	25,117
Derivative assets	0	189
Total assets	3,440	25,306
Derivative liabilities	0	0
Total liabilities	0	2,609
Net (income) loss attributable to non-controlling interests in 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
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level I | Options and futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	189
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level I | Corporate debt – bank debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level I | Corporate debt – all other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	634
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level I | Equities – common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	3,440	24,483
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level I | Equities – preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level I | Real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level II
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	6,709,375	6,180,346
Derivative assets	3,350	2,275
Total assets	6,712,725	6,182,621
Derivative liabilities	(1,157)	(643)
Total liabilities	4,313,180	4,128,637
Net (income) loss attributable to non-controlling interests in 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	3,350	2,275
Derivative liabilities	(1,157)	(643)
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level II | Options and futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level II | Corporate debt – bank debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	5,446,582	5,216,923
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level II | Corporate debt – all other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	1,262,793	963,423
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level II | Equities – common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level II | Equities – preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level II | Real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level III
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	226,689	325,922
Derivative assets	0	0
Total assets	226,689	325,922
Derivative liabilities	0	0
Total liabilities	0	0
Net (income) loss attributable to non-controlling interests in 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
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level III | Options and futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level III | Corporate debt – bank debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	101,495	136,055
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level III | Corporate debt – all other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	23,208	185,378
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level III | Equities – common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	42,972	3,063
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level III | Equities – preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	1,934	1,426
Net (income) loss attributable to non-controlling interests in consolidated funds | Fair Value, Measurements, Recurring | Level III | Real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	$ 57,080	$ 0