STOCKHOLDERS' EQUITY (Details 3) (Stock options, USD $)	9 Months Ended
	Sep. 30, 2013
Stock options
Number of Shares
Balance at the beginning of the period (in shares)	4,003,166
Granted (in shares)	808,815
Exercised (in shares)	(618,952)
Forfeited (in shares)	(319,475)
Expired (in shares)	(1,687)
Balance at the end of the period (in shares)	3,871,867
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 7.86
Granted (in dollars per share)	$ 27.29
Exercised (in dollars per share)	$ 4.92
Forfeited (in dollars per share)	$ 10.62
Expired (in dollars per share)	$ 7.24
Balance at the end of the period (in dollars per share)	$ 12.16