CONVERTIBLE NOTE HEDGE AND WARRANTS (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		12 Months Ended
	May 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 24, 2017
Debt Disclosure [Abstract]
Net proceeds from the Convertible Notes used to pay for the cost of the Convertible Note Hedge	$ 18,100
Payments for Hedge, Financing Activities	$ 61,500	$ 61,500	$ 0	$ 0
Number of Shares Covered by the Hedge Transactions	1.4
Debt Instrument, Convertible, Conversion Price	$ 207.63
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 266.39
Premium of warrant strike price over sales price of common stock	70.00%
Share price		$ 340.45			$ 156.70
Proceeds from the sale of warrants	$ 43,400	$ 43,410	$ 0	$ 0