Income taxes - Domestic and Foreign Components of Income (Loss) before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Domestic	$ (80,243)	$ (77,212)	$ (69,161)
Foreign	1,400	2,741	833
Net loss before taxes	$ (78,843)	$ (74,471)	$ (68,328)