Significant agreements - Collaboration revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Significant agreements.
Collaboration revenues	$ 5,352	$ 3,040	$ 21,645	$ 11,278
Bayer
Significant agreements.
Collaboration revenues	434	0	434	0
Novartis
Significant agreements.
Collaboration revenues	772	0	772	0
Ionis
Significant agreements.
Collaboration revenues	2,782	2,195	8,123	6,764
Genentech
Significant agreements.
Collaboration revenues	1,364	798	11,112	3,144
Dementia Discovery Fund
Significant agreements.
Collaboration revenues		47		205
AstraZeneca
Significant agreements.
Collaboration revenues	$ 0	$ 0	$ 1,204	$ 1,165