CONVERTIBLE NOTES (Details) $ / shares in Units, $ in Thousands		3 Months Ended
	Jan. 17, 2018 USD ($)	Mar. 31, 2018 USD ($) $ / shares
Debt Instrument [Line Items]
Proceeds from issuance of notes		$ 671,091
Debt, net of discounts and deferred financing costs:
Principal		690,000
Debt discount, net		(190,206)
Deferred financing costs		(13,106)
Total		$ 486,688
Convertible Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 690,000
Fixed interest rate (as a percent)	1.00%
Proceeds from issuance of notes	$ 671,100
Conversion rate, number of shares to be issued per $1000 of principal amount (in shares)		13.2569
Conversion price (in dollars per share) | $ / shares		$ 75.43
Repurchase price, as percentage of principal amount, if company undergoes change of control		100
Liability component of debt		$ 495,100
Effective interest rate (as a percent)		6.00%
Equity component of debt		$ 194,900
Total transaction costs		$ 18,800
Interest expense amortization term		7 years
Convertible Notes | Maximum
Debt Instrument [Line Items]
Total transaction costs		$ 13,100