REVENUE Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of revenue [Line Items]
Revenue	$ 252,745	$ 272,776	$ 758,676	$ 781,579
Service revenue
Schedule of revenue [Line Items]
Revenue	239,782	245,469	715,386	689,880
Reimbursable expenses
Schedule of revenue [Line Items]
Revenue	12,080	26,456	41,317	89,242
Non-controlling interests
Schedule of revenue [Line Items]
Revenue	$ 883	$ 851	$ 1,973	$ 2,457