Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	6 Months Ended
	Jun. 30, 2020
Shares
Options outstanding, beginning balance (in shares)	5,691,474
Granted (in shares)	1,616,718
Exercised (in shares)	(141,157)
Canceled (in shares)	(781,463)
Options outstanding, ending balance (in shares)	6,385,572
Exercisable as of period end (in shares)	3,035,054
Weighted- Average Exercise Price
Options outstanding, beginning balance (in dollars per share)	$ 6.99
Granted (in dollars per share)	6.51
Exercised (in dollars per share)	1.67
Canceled (in dollars per share)	9.85
Options outstanding, ending balance (in dollars per share)	6.63
Exercisable as of period end (in dollars per share)	$ 5.12