Share-based compensation - Share Options (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Additional Information
Total share-based compensation expense	$ 9,282,000	$ 9,042,000
Stock option
Number of Shares
Outstanding number of shares at beginning	7,469,527
Granted	1,862,815
Exercised	(133,735)
Forfeited	(30,351)
Outstanding number of shares at end	9,168,256		7,469,527
Number of shares, vested and expected to vest	9,168,256
Number of shares, options exercisable	4,959,686
Weighted Average Exercise Price
Weighted average exercise price at beginning	$ 23.13
Granted	18.44
Exercised	13.98
Forfeited	27.43
Weighted average exercise price at ending	22.30		$ 23.13
Weighted average exercise price, vested and expected to vest	22.30
Weighted average exercise price, options exercisable	$ 20.12
Weighted Average Contractual Term
Weighted average contractual term, outstanding	0 years		6 years 9 months 29 days
Weighted average contractual term, vested and expected to vest	0 years
Weighted average contractual term ,options exercisable	0 years
Aggregate Intrinsic Value
Aggregate intrinsic value outstanding	$ 61,558,000		$ 21,920,000
Aggregate intrinsic value, vested and expected to vest	61,558,000
Aggregate intrinsic value, options exercisable	$ 45,394,000
Additional Information
Granted	$ 12.93	$ 20.95
Exercised	$ 1,000,000.0	$ 20,000
Total share-based compensation expense	$ 7,500,000	$ 7,400,000