UNITHOLDERS' CAPITAL - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Total unitholders’ capital	$ 2,423,663	$ 2,484,788	$ 2,487,717	$ 2,150,416	$ 2,057,076	$ 2,020,617
OCGH
Class of Stock [Line Items]
Unitholders' capital (in shares)	84,001,461		85,471,937
Total unitholders’ capital	$ 1,018,173		$ 1,086,693
Total weighted average units outstanding
Class of Stock [Line Items]
Total Oaktree Operating Group units (in shares)	159,650,948		157,133,560
Total unitholders’ capital	$ 1,935,063		$ 1,997,745
Equity Held by Third Parties
Class of Stock [Line Items]
Total unitholders’ capital	$ 4,566		$ 5,661