COST OF REVENUE (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Cost of Revenue [Abstract]
Compensation and benefits	$ 68,502	$ 39,600	$ 184,273	$ 108,923
Outside fees and services	62,086	56,611	186,279	137,851
Reimbursable expenses	39,149	29,496	100,220	73,061
Technology and telecommunications	13,388	5,459	34,078	18,010
Depreciation and amortization	5,599	3,095	15,678	10,350
Total	$ 188,724	$ 134,261	$ 520,528	$ 348,195