SEGMENT REPORTING (Reconciliation of Income Before Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Economic net income
Income (loss) before taxes	$ 62,046	$ (190,588)
Adjustments:
Equity compensation expenses	21,087	15,089
Operating segment
Economic net income
Income (loss) before taxes	62,046	(190,588)
Adjustments:
Amortization of intangibles	3,287	5,275
Depreciation expense	3,889	3,216
Equity compensation expenses	21,087	15,089
Acquisition and merger-related expenses	(319)	255,088
Placement fees and underwriting costs	1,664	3,439
Offering costs	0	660
Other non-cash expense	7	0
Economic net income	138,388	120,272
Total performance income - unrealized	(35,118)	(49,261)
Total performance related compensation - unrealized	11,009	35,401
Total investment (income) loss - unrealized	5,574	(9,534)
Realized income	119,853	96,878
Total performance income - realized	(23,107)	(8,805)
Total performance related compensation - realized	14,869	5,301
Total investment income - realized	(1,936)	(1,386)
Fee related earnings	109,679	91,988
Economic net income	138,388	120,272
Performance related earnings	28,709	28,284
Operating segment | Subsidiaries
Adjustments:
(Income) loss before taxes of non-controlling interests in Consolidated Funds, net of eliminations	640	0
Reconciling items
Adjustments:
Amortization of intangibles	3,287	5,275
Depreciation expense	3,889	3,216
Equity compensation expenses	21,087	15,089
Acquisition and merger-related expenses	(319)	275,336
Placement fees and underwriting costs	1,664	3,439
Offering costs	0	660
Other non-cash expense	7	0
Total consolidation adjustments and reconciling items	76,342	310,860
OMG
Adjustments:
OMG expenses, net	46,454	44,416
Economic net income	(46,454)	(44,416)
Total performance income - unrealized	0	0
Total investment (income) loss - unrealized	(1,231)	1,407
Realized income	(47,780)	(43,205)
Total performance income - realized	0	0
Total performance related compensation - realized	0	0
Total investment income - realized	(2,768)	(850)
Fee related earnings	(49,222)	(45,266)
Economic net income	(46,454)	(44,416)
Performance related earnings	2,768	850
Consolidated Funds
Adjustments:
(Income) loss before taxes of non-controlling interests in Consolidated Funds, net of eliminations	367	15,855
Total investment income - realized	(64,422)	(41,492)
Consolidated Funds | Operating segment
Adjustments:
(Income) loss before taxes of non-controlling interests in Consolidated Funds, net of eliminations	$ (367)	$ (16,323)