Stock-based compensation - Stock Options (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Shares
Outstanding at the beginning of the period (in shares)	16,264,098
Granted (in shares)	940,375
Exercised (in shares)	(98,176)
Forfeited/cancelled (in shares)	(3,452,122)
Outstanding at the end of the period (in shares)	13,654,175		16,264,098
Vested at the end of the period (in shares)	7,792,304
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 3.56
Granted (in dollars per share)	1.26
Exercised (in dollars per share)	1.20
Forfeited/cancelled (in dollars per share)	5.55
Outstanding at the end of the period (in dollars per share)	2.92		$ 3.56
Vested at the end of the period (in dollars per share)	$ 3.45
Weighted-average remaining contractual term
Outstanding at the end of the period	7 years 2 months 12 days		6 years 8 months 12 days
Vested at the end of the period	6 years
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars)	$ 2,601
Outstanding at the end of the period (in dollars)			$ 2,601
Assumptions used to estimate fair value of each stock-based award on the grant date
Risk-free interest rate (as a percent)	2.83%	0.76%
Volatility (as a percent)	87.00%	95.00%
Dividend yield (as a percent)	0.00%	0.00%
Expected term (years)	5 years 8 months 12 days	5 years 10 months 24 days