COST OF REVENUE (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
COST OF REVENUE
Compensation and benefits	$ 39,600	$ 28,840	$ 108,923	$ 84,314
Outside fees and services	56,611	31,084	137,851	91,494
Reimbursable expenses	29,496	24,326	73,061	77,846
Technology and telecommunications	5,459	6,900	18,010	17,890
Depreciation and amortization	3,095	3,137	10,350	7,241
Total	$ 134,261	$ 94,287	$ 348,195	$ 278,785