Significant agreements - AstraZeneca Collaboration Agreement (Details) $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	May 31, 2018 USD ($) employee	Nov. 30, 2016 item	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2019 USD ($)
Significant agreements.
Collaboration revenues			$ 3,860	$ 1,808
Deferred revenue			65,578		$ 35,156	$ 71,340
AstraZeneca
Significant agreements.
Option fee for development and exploitation rights	$ 5,000
Transaction price	5,700
Collaboration revenues			0	277
Deferred revenue			2,295		3,756	2,361
AstraZeneca | Development milestone
Significant agreements.
Transaction price	700
AstraZeneca | Target Three Research License and Related Services
Significant agreements.
Collaboration revenues			0	$ 300
AstraZeneca | Development Milestone | Development milestone
Significant agreements.
Customer option payment	29,000
AstraZeneca | Regulatory Milestone | Regulatory milestone
Significant agreements.
Customer option payment	23,000
AstraZeneca | Commercial milestone | Commercial milestone
Significant agreements.
Customer option payment	$ 110,000
AstraZeneca | 2016 Collaboration Agreement
Significant agreements.
Biological Targets | item		2
AstraZeneca | May 2018 Option Exercise
Significant agreements.
Number of FTE | employee	2
Transaction price	$ 5,000		5,650				$ 6,300
AstraZeneca | May 2018 Option Exercise | Commercialization license per candidate
Significant agreements.
Customer option payment	$ 8,000
AstraZeneca | May 2018 Option Exercise | Target Three Research License and Related Services
Significant agreements.
Transaction price			650
AstraZeneca | May 2018 Option Exercise | Target 3 Material Right
Significant agreements.
Transaction price			1,504
Collaboration revenues					$ 1,500
AstraZeneca | May 2018 Option Exercise | Target 4 Material Right
Significant agreements.
Transaction price			1,204
AstraZeneca | May 2018 Option Exercise | Target 5 Material Right
Significant agreements.
Transaction price			1,165
AstraZeneca | May 2018 Option Exercise | Target 6 Material Right
Significant agreements.
Transaction price			$ 1,127
Deferred revenue						$ 1,100