STOCKHOLDERS' EQUITY AND SHARE-BASED COMPENSATION (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number of Options
Outstanding at the beginning of the period (in shares)	3,243,958
Granted (in shares)	278,500	200,000	900,000
Exercised (in shares)	(285,054)
Forfeited (in shares)	(179,095)
Outstanding at the end of the period (in shares)	3,058,309	3,243,958
Exercisable at the end of the period (in shares)	2,235,923
Weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 14.19
Granted (in dollars per share)	$ 69.48	$ 33.15	$ 23.58
Exercised (in dollars per share)	$ 12.19
Forfeited (in dollars per share)	$ 28.35
Outstanding at the end of the period (in dollars per share)	$ 17.69	$ 14.19
Exercisable at the end of the period (in dollars per share)	$ 11.59
Weighted average contractual term
Weighted average contractual term	6 years 1 month 10 days	6 years 8 months 12 days
Exercisable at the end of the period	5 years 6 months 7 days
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars)	$ 116,755
Outstanding at the end of the period (in dollars)	211,072	116,755
Exercisable at the end of the period (in dollars)	$ 167,885