COST OF REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Cost of Revenue [Abstract]
Compensation and benefits	$ 66,357	$ 62,997	$ 201,193	$ 197,213
Outside fees and services	77,445	66,952	222,574	175,021
Reimbursable expenses	12,080	26,456	41,317	89,242
Technology and telecommunications	11,502	10,630	32,145	32,878
Depreciation and amortization	6,618	6,815	20,007	20,481
Total	$ 174,002	$ 173,850	$ 517,236	$ 514,835