Share-based compensation - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025
Number of shares
Options, Beginning balance	15,856,758
Options, Granted	4,314,782
Options, Exercised	(514,257)
Options, Forfeited	(293,140)
Options, Expired	(3,187)
Options, Ending balance	19,360,956		15,856,758
Options, Exercisable	8,384,450
Weighted Average Exercise price
Beginning price	$ 10.15
Granted	22.11
Exercised	7.12
Forfeited	11.4
Expired	13.43
Ending price	12.88		$ 10.15
Exercisable	$ 9.29
Weighted average remaining contractual term
Weighted Average Remaining Contractual Term	8 years 2 months 4 days		8 years 5 months 26 days
Weighted Average Remaining Contractual Term, Exercisable	7 years 4 months 9 days
Intrinsic value, outstanding	$ 171,248		$ 180,668
Intrinsic value, exercisable	$ 103,082
Weighted average grant date fair value	$ 17.34	$ 7.53
Intrinsic value, exercised	$ 7,900	$ 2,500