REVENUE REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule of revenue [Line Items]
Revenue	$ 250,685	$ 255,799	$ 491,168	$ 505,931
Service revenue
Schedule of revenue [Line Items]
Revenue	238,107	241,324	467,946	475,604
Reimbursable expenses
Schedule of revenue [Line Items]
Revenue	11,891	13,783	21,920	29,237
Non-controlling interests
Schedule of revenue [Line Items]
Revenue	$ 687	$ 692	$ 1,302	$ 1,090

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration