Convertible Senior Notes Due 2023 - Summary of liability component of 2023 Notes (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total carrying value	$ 361,751,000	$ 345,170,000
Convertible Debt
Debt Instrument [Line Items]
2023 Notes	402,500,000	402,500,000
Unamortized debt discount and deferred financing costs	(40,749,000)	(57,330,000)
Total carrying value	$ 361,751,000	$ 345,170,000

Carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Convertible Notes Payable, excluding current portion. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.

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