Net Loss Per Share - Weighted-Average Anti-Dilutive Shares of Common Stock Excluded from the 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]
Weighted-average anti-dilutive shares of common stock (in shares)	50,622	74,292
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive shares of common stock (in shares)	15,929	22,136
Unvested restricted stock units and restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive shares of common stock (in shares)	34,693	52,156