BUSINESS INFORMATION (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) item	Mar. 31, 2015 USD ($) item	Dec. 31, 2015 USD ($)
Business information
Total revenues	$ 126,364	$ 99,412
Total assets	$ 388,428		$ 539,461
Client | Revenue
Business information
Number of clients | item	2	1
Client | Revenue | Minimum
Business information
Concentration risk (as a percent)	10.00%	10.00%
United States
Business information
Total revenues	$ 106,733	$ 69,431
Total assets	336,257		463,984
Europe
Business information
Total revenues	10,794	25,422
Total assets	21,452		45,067
Rest of World
Business information
Total revenues	8,837	$ 4,559
Total assets	$ 30,719		$ 30,410