STOCK-BASED COMPENSATION - Stock Option Activity (Details) - Employee Stock Option $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Number of Options
Options outstanding at January 1, 2016 | shares	7,450,914
Options granted | shares	296,692
Options exercised | shares	(807,677)
Options forfeited/cancelled | shares	(186,234)
Options outstanding at September 30, 2016 | shares	6,753,695
Options vested and exercisable at September 30, 2016 | shares	3,428,390
Options expected to vest | shares	3,149,286
Weighted Average Exercise Price
Options outstanding at January 1, 2016 | $ / shares	$ 34.07
Options granted | $ / shares	70.56
Options exercised | $ / shares	19.93
Options forfeited/cancelled | $ / shares	47.04
Options outstanding at September 30, 2016 | $ / shares	37.01
Options vested and exercisable at September 30, 2016 | $ / shares	25.74
Options expected to vest | $ / shares	$ 48.25
Aggregate Intrinsic Value
Options outstanding at January 1, 2016 | $	$ 331,938
Options granted | $	(371)
Options exercised | $	(39,883)
Options forfeited/cancelled | $	(4,147)
Options outstanding at September 30, 2016 | $	218,144
Options vested and exercisable at September 30, 2016 | $	149,375
Options expected to vest | $	$ 66,324