SHARE-BASED COMPENSATION (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended		12 Months Ended	9 Months Ended	28 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 May 2010 share repurchase program	Sep. 30, 2012 May 2010 share repurchase program	Sep. 30, 2012 2012 Share Repurchase Program	May 30, 2012 2012 Share Repurchase Program Maximum
Number of options
Outstanding at the beginning of the period (in shares)	3,243,958
Granted (in shares)	278,500	200,000
Exercised (in shares)	(221,615)
Forfeited (in shares)	(179,095)
Outstanding at the end of the period (in shares)	3,121,748		3,243,958
Exercisable at the end of the period (in shares)	1,936,789
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
Exercised (in dollars per share)	$ 13.00
Forfeited (in dollars per share)	$ 28.35
Outstanding at the end of the period (in dollars per share)	$ 18.28		$ 14.19
Exercisable at the end of the period (in dollars per share)	$ 11.28
Weighted average contractual term (in years)
Weighted average contractual term	6 years 3 months 18 days		6 years 8 months 12 days
Exercisable at the end of the period	5 years 7 months 6 days
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars)	$ 116,755
Outstanding at the end of the period (in dollars)	212,188		116,755
Exercisable at the end of the period (in dollars)	$ 145,205
Stock Repurchase Authorization
Number of shares of common stock authorized to be purchased							3,500,000
Number of shares of common stock purchased				300,000	2,500,000
Average purchase price per share (in dollars per share)				$ 63.25	$ 37.49
Number of shares still available for purchase						3,500,000