Equity Incentive Plans - Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Shares Underlying Stock Options
Outstanding beginning balance, Shares underlying stock options and restricted stock awards (in shares) | shares	5,616,840
Granted, Shares underlying stock options and restricted stock awards (in shares) | shares	3,458,513
Exercised, Shares underlying stock options and restricted stock awards (in shares) | shares	(94,219)
Cancelled/Forfeited, Shares underlying stock options and restricted stock awards (in shares) | shares	(4,859,468)
Outstanding ending balance, Shares underlying stock options and restricted stock awards (in shares) | shares	4,121,666
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Shares | shares	1,072,061
Weighted- Average Exercise Price per Share
Outstanding beginning balance, Weighted - average exercise price (usd per share) | $ / shares	$ 19.50
Granted, Weighted - average exercise price (usd per share) | $ / shares	4.61
Exercised, Weighted - average exercise price (usd per share) | $ / shares	6.42
Cancelled/forfeited, Weighted - average exercise price (usd per share) | $ / shares	18.34
Outstanding ending balance, Weighted - average exercise price (usd per share) | $ / shares	8.67
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 18.37
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	8 years 5 months 23 days	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	5 years 11 months 12 days	[1]
Outstanding, Aggregate Intrinsic Value | $	$ 7,792	[2]
Exercisable, Aggregate Intrinsic Value | $	$ 1,544	[2]

[1] Represents the weighted-average remaining contractual term of stock options

[2] Aggregate intrinsic value represents the product of the number of equity awards outstanding or equity awards exercisable multiplied by the difference between the Company’s closing stock price per share on the last trading day of the period, which was $3.88 as of December 31, 2020, and the exercise price.