Convertible Senior Notes - Schedule of the Liability and Equity Components of the Convertible Senior Notes (Details) - Convertible Senior Notes - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Series A Notes
Debt Instrument [Line Items]
Principal	$ 460,000	$ 460,000
Less: Convertible senior notes discounts and issuance costs, net of amortization	(88,726)	(93,469)
Net carrying amount	371,274	366,531
Equity component, net of issuance costs	92,567	92,567
Series B Notes
Debt Instrument [Line Items]
Principal	460,000	460,000
Less: Convertible senior notes discounts and issuance costs, net of amortization	(116,296)	(120,333)
Net carrying amount	343,704	339,667
Equity component, net of issuance costs	$ 117,834	$ 117,834