Stockholders' equity - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock Option Activity
Options outstanding at beginning of period (in shares)	5,840,538
Options granted (in shares)	2,404,300
Options exercised (in shares)	(882,624)
Options cancelled/forfeited (in shares)	(515,925)
Options outstanding at end of period (in shares)	6,846,289	5,840,538
Stock Options Weighted Average Exercise Price
Options outstanding at beginning of period (in dollars per share)	$ 5.11
Options granted (in dollars per share)	11.6
Options exercised (in dollars per share)	6.42
Options cancelled/forfeited (in dollars per share)	15.69
Options outstanding at end of period (in dollars per share)	$ 6.42	$ 5.11
Stock Option Activity, Additional Disclosure
Options outstanding, Weighted average remaining contractual life (in years)	8 years 8 months 12 days	7 years 8 months 12 days
Options outstanding at beginning of period, Aggregate intrinsic value (in dollars)	$ 45,037
Options outstanding at end of period, Aggregate intrinsic value (in dollars)	$ 53,127	$ 45,037
Options exercisable, Number of options (in shares)	1,878,082
Options exercisable, Weighted average exercise price (in dollars per share)	$ 5.02
Options exercisable, Weighted average remaining contractual life (in years)	7 years 8 months 12 days
Options exercisable, Aggregate intrinsic value (in dollars)	$ 17,547