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Net Loss per Share Attributable to Common Stock - Summary of Anti-dilutive Stock Equivalents (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	22,175,834	12,815,593	12,700,051
1.75% Convertible Senior Notes due 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Debt conversion, original debt, amount	$ 1,849
Options outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	5,733,738	7,792,181	9,435,349
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	4,443,315	5,023,412	3,264,702
Restricted Stock Units \| Non-employee Directors
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	16,428
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	2,040,000	0	0
Convertible Debt \| 1.75% Convertible Senior Notes due 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	838,821	0	0
Convertible Debt \| Convertible Senior Notes due 2025
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	9,119,960	0	0