Significant agreements - Summary of Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contract assets
Additions		$ 149
Deductions		(149)
Contract liabilities:
Beginning Balance	$ 5,657	14,635
Additions	35,085	1,172
Deductions	(8,028)	(10,413)	$ (4,472)
Impact of Exchange Rates	2,442	263
Ending Balance	35,156	5,657	14,635
AstraZeneca
Contract liabilities:
Beginning Balance	4,913	4,727
Additions	585	58
Deductions	(2,696)	(35)
Impact of Exchange Rates	954	163
Ending Balance	3,756	4,913	4,727
Sanofi
Contract liabilities:
Beginning Balance	0	9,908
Deductions		(9,984)
Impact of Exchange Rates		76
Ending Balance	0	0	$ 9,908
Dementia Discovery Fund
Contract liabilities:
Beginning Balance	744
Additions	500	1,114
Deductions	(436)	(394)
Impact of Exchange Rates	13	24
Ending Balance	821	$ 744
Genentech
Contract liabilities:
Additions	31,000
Deductions	(4,896)
Impact of Exchange Rates	1,475
Ending Balance	27,579
Evaluation and Option Agreement
Contract liabilities:
Additions	3,000
Ending Balance	$ 3,000

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Amount of increase from purchase of right to consideration in exchange for good or service transferred to customer when right is conditioned on passage of time.

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