FAIR VALUE - Financial Instruments by Fair-value Hierarchy Level (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	$ 3,580	$ 16,499
Derivative liabilities	(13,668)	(8,951)
Oaktree Capital Group Excluding Consolidated Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury and government-agency securities	555,008	757,578
Corporate investments	1,016,078	1,123,732
Derivative liabilities		(7,865)
Oaktree Capital Group Excluding Consolidated Funds | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		(60)
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	663,619	875,934
Total liabilities	(36,925)	(31,432)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Contingent consideration liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	(24,029)	(23,567)
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 asset	3,102	16,142
Derivative liabilities	(12,896)	(7,805)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	(60)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | U.S. Treasury and time deposit securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury and government-agency securities	555,008	757,578
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]
Corporate investments	105,509	102,214
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	555,008	757,578
Total liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I | Contingent consideration 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 I | Foreign-currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level I | U.S. Treasury and time deposit securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury and government-agency securities	555,008	757,578
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]
Corporate 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	30,954	43,693
Total liabilities	(12,896)	(7,865)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | Contingent consideration 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 | Foreign-currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	3,102	16,142
Derivative liabilities	(12,896)	(7,805)
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 asset		5,377
Derivative liabilities	(6,120)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	(60)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level II | U.S. Treasury and time deposit securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury and government-agency securities	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]
Corporate investments	27,852	27,551
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	77,657	74,663
Total liabilities	(24,029)	(23,567)
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | Contingent consideration liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	(24,029)	(23,567)
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 asset	0	0
Derivative liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Oaktree Capital Group Excluding Consolidated Funds | Fair Value, Measurements, Recurring | Level III | U.S. Treasury and time deposit securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury and government-agency securities	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]
Corporate investments	$ 77,657	$ 74,663