Share-based compensation - Share Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Additional Information
Total share-based compensation expense	$ 7,430	$ 5,368	$ 24,665	$ 21,239
Stock option
Number of Shares
Outstanding number of shares at beginning			5,898,888
Granted			1,859,315
Exercised			(26,562)
Forfeited			(419,621)
Outstanding number of shares at end	7,312,020		7,312,020		5,898,888
Number of shares, vested and expected to vest	7,312,020		7,312,020
Number of shares, options exercisable	4,334,755		4,334,755
Weighted Average Exercise Price
Weighted average exercise price at beginning			$ 22.45
Granted			27.57
Exercised			11.42
Forfeited			30.69
Weighted average exercise price at ending	$ 23.32		23.32		$ 22.45
Weighted average exercise price, vested and expected to vest	23.32		23.32
Weighted average exercise price, options exercisable	$ 18.39		$ 18.39
Weighted Average Contractual Term
Weighted average contractual term, outstanding			6 years 11 months 26 days		7 years 7 months 20 days
Weighted average contractual term, vested and expected to vest			6 years 11 months 26 days
Weighted average contractual term ,options exercisable			5 years 9 months
Aggregate Intrinsic Value
Aggregate intrinsic value outstanding	$ 29,629		$ 29,629		$ 71,002
Aggregate intrinsic value, vested and expected to vest	29,629		29,629
Aggregate intrinsic value, options exercisable	28,069		$ 28,069
Additional Information
Granted			$ 20.16	$ 32.91
Exercised	100	100	$ 300	$ 1,300
Total share-based compensation expense	$ 6,300	$ 4,700	$ 20,500	$ 17,100