REVENUE Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of revenue [Line Items]
Revenue	$ 255,799	$ 268,321	$ 505,931	$ 508,803
Service Revenue
Schedule of revenue [Line Items]
Revenue	241,324	236,595	475,604	444,411
Reimbursable Expenses
Schedule of revenue [Line Items]
Revenue	13,783	30,830	29,237	62,786
Non-controlling Interests
Schedule of revenue [Line Items]
Revenue	$ 692	$ 896	$ 1,090	$ 1,606