COST OF REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Cost of Revenue [Abstract]
Compensation and benefits	$ 64,890	$ 63,121	$ 134,216	$ 115,771
Outside fees and services	54,822	71,365	108,069	124,193
Reimbursable expenses	30,830	32,276	62,786	61,071
Technology and telecommunications	10,355	11,849	22,248	20,690
Depreciation and amortization	7,262	5,388	13,666	10,079
Total	$ 168,159	$ 183,999	$ 340,985	$ 331,804