Stockholders' equity - Stock options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Stock Options, Additional Disclosures
Outstanding, Number, Beginning Balance (in shares)	4,700	4,560
Granted (in shares)		3,125
Forfeited and cancelled (in shares)		(2,985)
Outstanding, Number, Ending Balance (in shares)	4,700	4,700	4,560
Options Exercisable, Number, Beginning	4,577	2,238
Options Exercisable, Number, Ending	4,695	4,577	2,238
Outstanding, Weighted Average Exercise Price, Beginning Balance (in dollars per share)	$ 398.3	$ 796.96
Granted (in dollars per share)		5.36
Forfeited and cancelled (in dollars per share)		596.32
Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)	398.3	398.3	$ 796.96
Options Exercisable, Exercise price, beginning (in dollars per share)	391.04	1,173.6
Options Exercisable, Exercise price, ending (in dollars per share)	$ 398.46	$ 391.04	$ 1,173.6
Options, Outstanding, Remaining Contractual Term	7 years 6 months	8 years 7 months 6 days	8 years 6 months
Vested and exercisable (years)	7 years 6 months	8 years 7 months 6 days	8 years 1 month 6 days
Options Exercisable, Intrinsic value	$ 0	$ 0