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Significant agreements - AstraZeneca Collaboration Agreement (Details) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	May 31, 2018 USD ($)	Nov. 30, 2016 item	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2019 USD ($)
Significant agreements.
Collaboration revenues			$ 11,397	$ 4,378	$ 16,293	$ 8,238
Deferred revenue			144,837		144,837		$ 61,873	$ 71,340
AstraZeneca
Significant agreements.
Option fee for development and exploitation rights	$ 5,000
Transaction price	5,700
Collaboration revenues			1,204	$ 1,165	1,204	$ 1,165
Deferred revenue			0		0		$ 1,076	$ 2,361
AstraZeneca \| Development Milestone
Significant agreements.
Transaction price	700
AstraZeneca \| 2016 Collaboration Agreement
Significant agreements.
Biological Targets \| item		2
AstraZeneca \| May 2018 Option Exercise
Significant agreements.
Option fee for development and exploitation rights	$ 5,000
Transaction price			5,650		5,650				$ 6,300
AstraZeneca \| May 2018 Option Exercise \| Target Three Research License and Related Services
Significant agreements.
Transaction price			650		650
AstraZeneca \| May 2018 Option Exercise \| Target 3 Material Right
Significant agreements.
Transaction price			1,504		1,504
AstraZeneca \| May 2018 Option Exercise \| Target 4 Material Right
Significant agreements.
Transaction price			1,204		1,204
AstraZeneca \| May 2018 Option Exercise \| Target 5 Material Right
Significant agreements.
Transaction price			1,165		1,165
AstraZeneca \| May 2018 Option Exercise \| Target 6 Material Right
Significant agreements.
Transaction price			$ 1,127		$ 1,127