Income taxes - Schedule of deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating losses	$ 61,036	$ 54,300
Capitalized research and experimental expenditures	51,401	27,568
Operating lease liability	20,611	21,443
R&D and investment tax credits	18,049	11,519
Stock-based compensation	9,061	6,296
Deferred revenue	3,881	8,457
Foreign tax credit	1,204	0
Capitalized start-up costs	555	699
Unrealized gain/loss	0	1,090
Other	27	354
Total gross deferred tax assets	165,825	131,726
Deferred tax liabilities:
Right-of-use asset	(18,573)	(19,868)
Fixed assets	(1,663)	(1,738)
Less: valuation allowance	(145,589)	(110,120)
Net deferred taxes	$ 0	$ 0