INVESTMENTS - Net Gains (Losses) from Investment Activities of Consolidated Funds (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Gain (Loss) on Securities [Line Items]
Net realized loss on consolidated funds’ investments	$ (39,247)	$ (5,819)
Net change in unrealized appreciation (depreciation) on consolidated funds’ investments	(326,067)	57,117
Consolidated Funds \| Not Designated as Hedging Instrument
Gain (Loss) on Securities [Line Items]
Net realized loss on consolidated funds’ investments	(39,247)	(5,819)
Net change in unrealized appreciation (depreciation) on consolidated funds’ investments	(326,067)	57,117
Net Realized Gain (Loss) on Investments	(11,973)	2,126
Net Change in Unrealized Appreciation (Depreciation) on Investments	(23,194)	(470)
Consolidated Funds \| Investments and other financial instruments \| Not Designated as Hedging Instrument
Gain (Loss) on Securities [Line Items]
Net realized loss on consolidated funds’ investments	(27,274)	(7,945)
Net change in unrealized appreciation (depreciation) on consolidated funds’ investments	(895,927)	129,670
Consolidated Funds \| CLO Liabilities \| Not Designated as Hedging Instrument
Gain (Loss) on Securities [Line Items]
Net realized loss on consolidated funds’ investments	0	0
Net change in unrealized appreciation (depreciation) on consolidated funds’ investments	593,054	(72,083)
Consolidated Funds \| Foreign-currency forward contracts \| Not Designated as Hedging Instrument
Gain (Loss) on Securities [Line Items]
Net Realized Gain (Loss) on Investments	(12,077)	2,126
Net Change in Unrealized Appreciation (Depreciation) on Investments	(23,073)	(470)
Consolidated Funds \| Options and futures \| Not Designated as Hedging Instrument
Gain (Loss) on Securities [Line Items]
Net Realized Gain (Loss) on Investments	104	0
Net Change in Unrealized Appreciation (Depreciation) on Investments	$ (121)	$ 0

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.3(a))
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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of investments, not including unrealized gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, held at each balance sheet date and included in earnings for the period.

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