Commitments and contingencies - Components of lease expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Commitments and contingencies
Operating lease cost	$ 3,790	$ 1,224	$ 896
Variable lease cost	1,643	612	662
Total lease cost	$ 5,433	$ 1,836	$ 1,558
Weighted-average remaining operating lease term (years)	4 years 2 months 12 days	4 years 9 months 18 days
Weighted-average discount rate	7.00%	7.10%