GOODWILL AND INTANGIBLE ASSETS (Carrying Value of Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Finite-lived intangible assets, net
Intangible assets	$ 84,315			$ 84,315		$ 109,106
Less: accumulated amortization	(50,316)			(50,316)		(68,641)
Intangible assets, net	33,999			$ 33,999		40,465
Fully-amortized intangibles, amount removed during the period		$ 25,000
Service fee period				12 months
General, administrative and other expense
Finite-lived intangible assets, net
Amortization expense	3,300		$ 5,200	$ 6,600	$ 10,500
Management contracts
Finite-lived intangible assets, net
Weighted average amortization period				3 years
Intangible assets	42,335			$ 42,335		67,306
Client relationships
Finite-lived intangible assets, net
Weighted average amortization period				10 years
Intangible assets	38,600			$ 38,600		38,600
Trade name
Finite-lived intangible assets, net
Weighted average amortization period				4 years
Intangible assets	3,200			$ 3,200		3,200
Other(1)
Finite-lived intangible assets, net
Weighted average amortization period				8 months 12 days
Intangible assets	$ 180			$ 180		$ 0