Commitments and contingencies - Components of lease expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Commitments and contingencies
Operating lease cost	$ 1,326	$ 906
Variable lease cost	648	267
Total lease cost	$ 1,974	$ 1,173
Weighted-average remaining operating lease term (years)	3 years 8 months 12 days	4 years 10 months 24 days
Weighted-average discount rate	7.62%	7.04%