Significant agreements - Collaboration revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Significant agreements.
Collaboration revenues	$ 4,896	$ 3,860
Ionis
Significant agreements.
Collaboration revenues	2,784	2,314
Genentech
Significant agreements.
Collaboration revenues	$ 2,112	1,474
Dementia Discovery Fund
Significant agreements.
Collaboration revenues		$ 72