COST OF REVENUE (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
COST OF REVENUE
Compensation and benefits	$ 36,744	$ 27,989	$ 69,323	$ 55,474
Outside fees and services	46,345	31,757	81,240	60,410
Reimbursable expenses	23,299	24,814	43,565	53,520
Technology and telecommunications	7,060	5,866	12,551	10,990
Depreciation and amortization	3,524	2,312	7,255	4,104
Total	$ 116,972	$ 92,738	$ 213,934	$ 184,498