Intangible assets - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Cost	$ 35,324	$ 35,324
Accumulated amortization	(25,283)	(20,998)
Net	10,041	14,326
Developed technology
Finite-Lived Intangible Assets [Line Items]
Cost	30,100	30,100
Accumulated amortization	(24,456)	(20,694)
Net	5,644	9,406
In-licensed rights
Finite-Lived Intangible Assets [Line Items]
Cost	5,224	5,224
Accumulated amortization	(827)	(304)
Net	$ 4,397	$ 4,920