COST OF REVENUE (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
COST OF REVENUE
Compensation and benefits	$ 63,121	$ 36,744	$ 115,771	$ 69,323
Outside fees and services	71,365	46,345	124,193	81,240
Reimbursable expenses	32,276	23,299	61,071	43,565
Technology and telecommunications	11,849	7,060	20,690	12,551
Depreciation and amortization	5,388	3,524	10,079	7,255
Total	$ 183,999	$ 116,972	$ 331,804	$ 213,934