UNITHOLDERS' CAPITAL - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			9 Months Ended
	Aug. 09, 2018	May 17, 2018	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Total unitholders’ capital			$ 1,612,550	$ 1,581,018	$ 1,702,169	$ 2,129,756	$ 2,423,663	$ 2,487,717
Non-controlling interests in consolidated subsidiaries			$ 443,908		$ 503,253
Preferred redemption price (in dollars per share)			$ 25.00
Preferred redemption notice period			30 days
Preferred redemption period, change in control event			60 days
Preferred redemption price, change in control event (in dollars per share)			$ 25.25
Redemption period after tax redemption event			60 days
Preferred redemption price, tax redemption event (in dollars per share)			$ 25.50
Series A Preferred Units
Class of Stock [Line Items]
Preferred dividend rate		6.625%
Preferred redemption price (in dollars per share)		$ 25.00
Sale of stock, consideration received		$ 173,700
Series A Preferred Units | Preferred Stock Issuance
Class of Stock [Line Items]
Number of shares issued during mergers (in shares)		7,200,000
Series B Preferred Units
Class of Stock [Line Items]
Preferred dividend rate	6.55%
Preferred redemption price (in dollars per share)	$ 25.00
Sale of stock, consideration received	$ 226,900
Series B Preferred Units | Preferred Stock Issuance
Class of Stock [Line Items]
Number of shares issued during mergers (in shares)	9,400,000
OCGH
Class of Stock [Line Items]
Unitholders' capital (in shares)			61,383,742		61,793,286
Non-controlling interests in consolidated subsidiaries			$ 443,908		$ 503,253
Total weighted average units outstanding
Class of Stock [Line Items]
Total Oaktree Operating Group units (in shares)					159,760,541
Total unitholders’ capital			$ 1,157,510		$ 1,301,066
Total weighted average units outstanding | Converted OCGH Units and OCGH Units
Class of Stock [Line Items]
Total Oaktree Operating Group units (in shares)			160,060,782