STOCK-BASED COMPENSATION (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Weighted-average assumptions used to estimate the fair value of options granted
Expected term	5 years 9 months 18 days
Stock options
Weighted-average assumptions used to estimate the fair value of options granted
Dividend yield (as a percent)	0.00%	0.00%
Expected volatility (as a percent)	37.10%	43.10%
Risk-free interest rate (as a percent)	1.60%	1.60%
Expected term		5 years 10 months 24 days
Stock Options, Number of Shares
Balance at the beginning of the period (in shares)	13,066
Granted (in shares)	903
Exercised (in shares)	(4,589)
Cancelled or forfeited (in shares)	(16)
Balance at the end of the period (in shares)	9,364		13,066
Vested and expected to vest in the future at the end of the period (in shares)	8,869
Exercisable at the end of the period (in shares)	6,284
Stock options, Weighted-Average Exercise Price Per Share
Balance at the beginning of the period (in dollars per share)	$ 19.73
Granted (in dollars per share)	$ 133.68
Exercised (in dollars per share)	$ 4.17
Cancelled or forfeited (in dollars per share)	$ 40.61
Balance at the end of the period (in dollars per share)	$ 38.30		$ 19.73
Vested and expected to vest in the future at the end of the period (in dollars per share)	$ 35.23
Exercisable at the end of the period (in dollars per share)	$ 17.00
Weighted-Average Remaining Contractual Term
Balance at the beginning of the period	4 years 9 months 18 days		3 years 1 month 6 days
Balance at the end of the period	4 years 9 months 18 days		3 years 1 month 6 days
Vested and expected to vest in the future at the end of the period	4 years 7 months 6 days
Exercisable at the end of the period	2 years 10 months 24 days
Aggregate Intrinsic Value
Balance at the beginning of the period	$ 1,158,412
Balance at the end of the period	937,246		1,158,412
Vested and expected to vest in the future at the end of the period	915,012
Exercisable at the end of the period	$ 762,806