COST OF REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cost of Revenue [Abstract]
Compensation and benefits	$ 69,773	$ 64,890	$ 134,836	$ 134,216
Outside fees and services	73,326	54,822	145,129	108,069
Reimbursable expenses	13,783	30,830	29,237	62,786
Technology and telecommunications	10,703	10,355	20,643	22,248
Depreciation and amortization	6,786	7,262	13,389	13,666
Total	$ 174,371	$ 168,159	$ 343,234	$ 340,985