Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	9 Months Ended
	Sep. 30, 2020
Shares
Options outstanding, beginning balance (in shares)	5,691,474
Granted (in shares)	2,028,718
Exercised (in shares)	(159,998)
Canceled (in shares)	(982,574)
Options outstanding, ending balance (in shares)	6,577,620
Exercisable as of period end (in shares)	3,363,541
Weighted- Average Exercise Price
Options outstanding, beginning balance (in dollars per share)	$ 6.99
Granted (in dollars per share)	6.09
Exercised (in dollars per share)	1.54
Canceled (in dollars per share)	8.83
Options outstanding, ending balance (in dollars per share)	6.57
Exercisable as of period end (in dollars per share)	$ 5.32