Debt Obligations - Schedule of Net Carrying Amount of Liability Component (Details) - 1.75% Convertible Senior Notes Due 2022 - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Principal	$ 200,000	$ 200,000
Unamortized debt discount	(23,623)	(31,132)
Unamortized debt issuance costs	(2,017)	(2,711)
Net carrying amount of the liability component	$ 174,360	$ 166,157