Significant agreements - Collaboration revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Significant agreements.
Collaboration revenues	$ 3,860	$ 1,808
Ionis
Significant agreements.
Collaboration revenues	2,314	0
Genentech
Significant agreements.
Collaboration revenues	1,474	1,448
Dementia Discovery Fund
Significant agreements.
Collaboration revenues	72	83
AstraZeneca
Significant agreements.
Collaboration revenues	$ 0	$ 277