Net Loss Per Share - Anti-Dilutive Securities of Common Stock Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	50,145	34,387
Series A Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	29	29
Options to purchase common stock and employee stock purchase plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	3,435	3,898
Unvested restricted share awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	9,781	8,866
Warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	19,654	21,594
Senior Convertible Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	17,246