Stock-based compensation - Summary of Stock Option Activity Under Plan (Details)	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Shares (in thousands)
Outstanding at beginning of period (in shares) | shares	4,227,000
Granted (in shares) | shares	3,010,000
Exercised (in shares) | shares	0
Canceled, forfeited, or expired (in shares) | shares	(905,000)
Outstanding at end of period (in shares) | shares	6,332,000
Exercisable at end of period (in shares) | shares	2,290,000
Vested and expected to vest at end of period (in shares) | shares	6,332,000
Weighted- average exercise price per share
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 14.16
Granted (in dollars per share) | $ / shares	1.47
Exercised (in dollars per share) | $ / shares	0
Canceled, forfeited, or expired (in dollars per share) | $ / shares	10.52
Outstanding at end of period (in dollars per share) | $ / shares	8.66
Exercisable at end of period (in dollars per share) | $ / shares	18.54
Vested and expected to vest at end of period (in dollars per share) | $ / shares	$ 8.66