Commitments and contingencies - Components of lease expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Commitments and contingencies
Operating lease cost	$ 1,367	$ 1,036	$ 2,693	$ 1,942
Variable lease cost	803	328	1,451	595
Total lease cost	$ 2,170	$ 1,364	$ 4,144	$ 2,537
Weighted-average remaining operating lease term (years)	3 years 4 months 24 days	4 years 8 months 12 days	3 years 4 months 24 days	4 years 8 months 12 days
Weighted-average discount rate	7.61%	7.04%	7.61%	7.04%