Significant agreements - Collaboration revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Significant agreements.
Collaboration revenues	$ 11,397	$ 4,378	$ 16,293	$ 8,238
Ionis
Significant agreements.
Collaboration revenues	2,557	2,255	5,341	4,569
Genentech
Significant agreements.
Collaboration revenues	7,636	872	9,748	2,346
Dementia Discovery Fund
Significant agreements.
Collaboration revenues		86		158
AstraZeneca
Significant agreements.
Collaboration revenues	$ 1,204	$ 1,165	$ 1,204	$ 1,165