Significant agreements - Summary of Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Contract assets
Additions	$ 149	$ 91
Deductions	(149)	(91)
Contract liabilities:
Balance at the beginning of year	14,635	14,467
Additions	1,172	5,350
Deductions	(10,413)	(4,472)
Impact of exchange rates	263	(710)
Balance at the end of year	5,657	14,635
AstraZeneca
Contract liabilities:
Balance at the beginning of year	4,727
Additions	58	5,350
Deductions	(35)	(466)
Impact of exchange rates	163	(157)
Balance at the end of year	4,913	4,727
Sanofi
Contract liabilities:
Balance at the beginning of year	9,908	14,467
Deductions	(9,984)	(4,006)
Impact of exchange rates	76	(553)
Balance at the end of year	0	$ 9,908
Dementia Discovery Fund
Contract liabilities:
Additions	1,114
Deductions	(394)
Impact of exchange rates	24
Balance at the end of year	$ 744