Convertible Senior Notes (Tables)

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Schedule of Carrying Values and Coupon Rates on Financing Arrangements

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

	March 31, 2019		December 31, 2018
Principal amount of 2019 Notes outstanding	$	27,323	$	27,326
Unamortized discount (including unamortized debt issuance cost)	(567)		(893)
Total current portion of notes payable	$	26,756	$	26,433
Principal amount of 2023 Notes outstanding	$	750,000	$	750,000
Unamortized discount (including unamortized debt issuance cost)	(133,013)		(140,136)
Total long-term portion of notes payable	$	616,987	$	609,864
Fair value of convertible senior notes outstanding (Level 2)	$	687,180	$	713,533