Stock-based compensation - Activity Under Stock Option Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Number of Shares
Outstanding at beginning of period (in shares)	8,342,429
Options granted (in shares)	2,793,659
Exercised (in shares)	(414,914)
Cancelled (in shares)	(669,891)
Outstanding at end of period (in shares)	10,051,283	8,342,429
Options exercisable, at end of period (in shares)	5,410,541
Weighted- Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 11.25
Granted (in dollars per share)	5.43
Exercised (in dollars per share)	3.21
Cancelled (in dollars per share)	13.09
Outstanding at end of period (in dollars per share)	9.84	$ 11.25
Options exercisable, at end of period (in dollars per share)	$ 9.45
Additional Disclosures
Weighted average remaining contractual term, options outstanding	7 years 2 months 12 days	7 years 2 months 12 days
Weighted average remaining contractual term, options exercisable	6 years 1 month 6 days
Aggregate intrinsic value, options outstanding	$ 8,197	$ 8,458
Aggregate intrinsic value, options exercisable	$ 6,076