Significant agreements - Collaboration revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Significant agreements.
Collaboration revenues	$ 14,463	$ 11,697	$ 10,390
Ionis
Significant agreements.
Collaboration revenues	9,347	4,242	0
Genentech
Significant agreements.
Collaboration revenues	3,565	5,660	4,896
Dementia Discovery Fund
Significant agreements.
Collaboration revenues	386	391	436
AstraZeneca
Significant agreements.
Collaboration revenues	$ 1,165	$ 1,404	2,696
Oxurion
Significant agreements.
Collaboration revenues			$ 2,362