UNITHOLDERS' CAPITAL - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Total unitholders’ capital	$ 2,009,269	$ 1,885,171	$ 1,814,755	$ 1,808,094
OCGH
Class of Stock [Line Items]
Unitholders' capital (in shares)	91,682,408	91,758,067
Total unitholders’ capital	$ 1,096,523	$ 1,040,274
Oaktree Operating Group
Class of Stock [Line Items]
Total Oaktree Operating Group units (in shares)	156,287,873	154,790,343
Total unitholders’ capital	$ 1,869,205	$ 1,754,882
Equity Held by Third Parties
Class of Stock [Line Items]
Total unitholders’ capital	$ 8,398	$ 10,045