Convertible Senior Notes (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Schedule of Equity and Liability Components of the Convertible Senior Notes

The following table summarizes information about the equity and liability components of the 2019 Notes and 2023 Notes (in thousands).

	December 31, 2018		December 31, 2017
Principle amount of 2019 Notes outstanding	$	27,326	$	245,000
Unamortized discount (including unamortized debt issuance cost)	(893)		(20,471)
Total current portion of notes payable	$	26,433	$	224,529
Principle amount of 2023 Notes outstanding	$	750,000	$	—
Unamortized discount (including unamortized debt issuance cost)	(140,136)		—
Total long-term portion of notes payable	$	609,864	$	—
Carrying value of equity component of 2023 Notes	$	127,997	$	—
Fair value of convertible senior notes outstanding (Level 2)	$	713,533	$	446,360