BUSINESS INFORMATION (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) client	Sep. 30, 2016 USD ($) client	Sep. 30, 2017 USD ($) client	Sep. 30, 2016 USD ($) client	Dec. 31, 2016 USD ($)
Business information
Total revenues	$ 170,041	$ 150,676	$ 515,448	$ 408,765
Total assets	$ 795,089		$ 795,089		$ 598,800
Client | Revenue
Business information
Number of clients | client	0	0	0	0
United States
Business information
Total revenues	$ 131,306	$ 125,380	$ 420,412	$ 338,332
Total assets	672,783		672,783		506,748
Europe
Business information
Total revenues	24,939	17,503	63,595	41,625
Total assets	41,418		41,418		31,341
Rest Of World
Business information
Total revenues	13,796	$ 7,793	31,441	$ 28,808
Total assets	$ 80,888		$ 80,888		$ 60,711