Net loss per share - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net loss	$ (55,987)	$ (53,344)	$ (31,083)	$ (25,831)	$ (109,331)	$ (56,914)	$ (151,759)	$ (112,033)
Denominator:
Weighted average common shares outstanding, basic	69,160,484		51,867,854		64,234,122	49,419,558
Weighted average common shares outstanding, diluted	69,160,484		51,867,854		64,234,122	49,419,558
Net loss per share, basic	$ (0.81)		$ (0.6)		$ (1.7)	$ (1.15)
Net loss per share, diluted	$ (0.81)		$ (0.6)		$ (1.7)	$ (1.15)