Significant agreements - Dementia Discovery Fund Agreement (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Dec. 31, 2020	May 31, 2019	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Significant agreements.
Collaboration revenues			$ 14,463	$ 11,697	$ 10,390
Deferred revenue	$ 35,156		61,873	71,340	35,156
Dementia Discovery Fund
Significant agreements.
Upfront cash payment		$ 1,100
Potential milestone payments		$ 700	600
Threshold period for exercising option to establish a jointly-owned new company		90 days
Option to purchase ownership of new entity		34.00%
Threshold period of notice required for termination of agreement		60 days
Transaction price		$ 1,100
Collaboration revenues			386	391	436
Deferred revenue	821		$ 0	$ 428	$ 821
Dementia Discovery Fund | NewCo
Significant agreements.
Option to purchase ownership of new entity		66.00%
Threshold period in which Newco shall have the right to initiate a new research program		2 years
Dementia Discovery Fund | NewCo | Maximum
Significant agreements.
Total voting rights related to ownership interests		50.00%
Dementia Discovery Fund | Specific scientific criteria milestone
Significant agreements.
Milestone payment received	$ 500