Equity Incentive Plans - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020
Shares Subject to Options
Stock options outstanding, beginning balance (in shares)	3,039,880
Granted (in shares)	461,425
Exercises (in shares)	(91,146)
Forfeitures and cancellations (in shares)	(534,096)
Stock options outstanding, ending balance (in shares)	2,876,063
Stock options exercisable, ending balance (in shares)	1,355,530
Weighted-Average Exercise Price per Share
Stock options outstanding, beginning balance (in dollars per share)	$ 29.40
Granted (in dollars per share)	18.30
Exercises (in dollars per share)	4.06
Forfeitures and cancellations (in dollars per share)	37.54
Stock options outstanding, ending balance (in dollars per share)	26.91
Stock options exercisable, ending balance (in dollars per share)	$ 27.48
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted average remaining contractual term, options outstanding (in years)	7 years 5 months 19 days
Weighted average remaining contractual term, options exercisable (in years)	5 years 7 months 20 days
Aggregate intrinsic value, options outstanding	$ 6,747
Aggregate intrinsic value, options exercisable	$ 6,365