Share based compensation - Weighted-Average Assumptions (Details) - Share Options - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	3.40%	2.09%
Risk-free interest rate, maximum	4.69%	4.20%
Expected volatility, minimum	80.64%	82.50%
Expected volatility, maximum	87.26%	84.27%
Expected dividend yield	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected lives, years	5 years	5 years
Grant date fair value (in dollars per share)	$ 1.69	$ 0.34
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected lives, years	7 years	7 years
Grant date fair value (in dollars per share)	$ 3.27	$ 1.33