SEGMENT REPORTING (Reconciliation of Income Before Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Economic net income
Income (loss) before taxes	$ 115,080	$ 83,006	$ (75,508)	$ 74,032
Adjustments:
Amortization of intangibles			10,500	14,400
Equity compensation expenses	18,917	9,536	34,006	18,709
Income tax expense (benefit)	(1,253)	4,434	33,011	(231)
Operating segment
Adjustments:
Amortization of intangibles	5,274	7,121	10,549	14,384
Depreciation expense	2,774	1,934	5,990	3,792
Equity compensation expenses	18,917	9,536	34,006	18,709
Acquisition and merger-related expenses	756	61	255,844	557
Placement fees and underwriting costs	6,383	1,754	9,822	2,684
Offering costs	(5)	0	655	0
Economic net income	209,630	154,681	330,338	222,106
Total performance fees income - realized	(74,130)	(81,604)	(82,935)	(87,953)
Total performance fees income - unrealized	(263,629)	(123,314)	(312,890)	(85,966)
Total performance fee compensation - realized	(52,973)	(51,031)	(58,274)	(53,014)
Total performance fee compensation - unrealized	208,732	100,865	244,133	77,552
Total investment income	(30,237)	(22,427)	(41,157)	(17,645)
Fee related earnings	103,339	79,232	195,763	161,108
Investment and other income (expense) realized, net	4,522	14,657	5,907	18,828
Dividend equivalent	(1,520)	(706)	(4,201)	(1,390)
One-time acquisition costs	(11)	(12)	(23)	(282)
Income tax expense (benefit)	(381)	(249)	(607)	(481)
Non-cash items	322	683	136	847
Placement fees and underwriting costs	(6,383)	(1,747)	(9,822)	(2,685)
Depreciation and amortization	(1,315)	(998)	(2,785)	(1,929)
Distributable earnings	119,730	121,433	209,029	208,955
Economic net income	209,630	154,681	330,338	222,106
Performance related earnings	106,291	75,449	134,575	60,998
Operating segment | Subsidiaries
Adjustments:
(Income) loss before taxes of non-controlling interests in Consolidated Funds, net of eliminations	623	0	623	0
Reconciling items
Adjustments:
Amortization of intangibles	5,274	7,121	10,549	14,384
Depreciation expense	2,774	1,934	5,990	3,792
Equity compensation expenses	18,917	9,536	34,006	18,709
Acquisition and merger-related expenses	724	85	276,060	353
Placement fees and underwriting costs	6,383	1,754	9,822	2,684
Offering costs	(5)	0	655	0
Total consolidation adjustments and reconciling items	94,550	71,675	405,846	148,074
OMG
Adjustments:
OMG expenses, net	51,577	52,330	96,429	95,607
Economic net income	(51,577)	(52,330)	(96,429)	(95,607)
Total performance fees income - realized	0	0	0	0
Total performance fees income - unrealized	0	0	0	0
Total performance fee compensation - realized	0	0	0	0
Total performance fee compensation - unrealized	0	0	0	0
Total investment income	1,626	12,663	776	13,112
Fee related earnings	(49,951)	(39,667)	(95,653)	(82,495)
Distributable earnings	(50,038)	(44,613)	(98,428)	(90,854)
Economic net income	(51,577)	(52,330)	(96,429)	(95,607)
Performance related earnings	(1,626)	(12,663)	(776)	(13,112)
Consolidated Funds
Adjustments:
(Income) loss before taxes of non-controlling interests in Consolidated Funds, net of eliminations	(8,647)	1,054	7,208	(10,925)
Total investment income	(11,451)	(9,690)	(21,621)	(17,022)
Consolidated Funds | Operating segment
Adjustments:
(Income) loss before taxes of non-controlling interests in Consolidated Funds, net of eliminations	$ 8,251	$ (1,061)	$ (8,072)	$ 12,341