Significant agreements - Collaboration revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Significant agreements.
Collaboration revenues	$ 3,040	$ 4,333	$ 11,278	$ 7,926
Ionis
Significant agreements.
Collaboration revenues	2,195	2,066	6,764	2,066
Genentech
Significant agreements.
Collaboration revenues	798	1,063	3,144	4,142
Dementia Discovery Fund
Significant agreements.
Collaboration revenues	47	77	205	314
AstraZeneca
Significant agreements.
Collaboration revenues	$ 0	$ 1,127	$ 1,165	$ 1,404