Stock-Based Compensation - Schedule of activity for service-based stock options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Options
Outstanding at the beginning of the period (in shares)	4,790,683
Granted (in shares)	2,033,760
Exercised (in shares)	(1,197,016)
Expired (in shares)	(36,561)
Forfeited (in shares)	(537,916)
Outstanding at the end of the period (in shares)	5,052,950	4,790,683
Exercisable at the end of the period (in shares)	2,385,824
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 5.85
Granted (in dollars per share)	17.51
Exercised (in dollars per share)	3.64
Expired (in dollars per share)	26.16
Forfeited (in dollars per share)	11.26
Outstanding at the end of the period (in dollars per share)	10.35	$ 5.85
Exercisable at the end of the period (in dollars per share)	$ 7.49
Weighted Average Remaining Contractual Term
Outstanding	7 years 8 months 12 days	7 years 8 months 12 days
Exercisable at end of period	6 years 6 months
Aggregate Intrinsic Value
Outstanding	$ 37,974	$ 11,407
Exercised	12,400	$ 10,300	$ 700
Exercisable at end of period	$ 25,113
Service-based stock options
Options
Granted (in shares)	2,033,760