Significant agreements - Genentech Collaboration Agreement (Details) $ in Thousands		1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 21, 2020 USD ($) item	Jun. 30, 2022 USD ($)	Oct. 31, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) item	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Significant agreements.
Collaboration revenues				$ 4,378	$ 1,785	$ 8,238	$ 3,593
Deferred revenue		$ 66,379		66,379		66,379		$ 71,340		$ 35,156
Genentech
Significant agreements.
Number of potential development candidates | item	4
Upfront cash payment	$ 30,000
Number of immuno oncology targets | item	2
Additional number of immuno oncology targets | item	2
Expansion Fee	$ 10,000
Milestone payments, receivable									$ 2,000
Transaction price	31,000	33,000		33,000		33,000			$ 33,000
Collaboration revenues				872	$ 1,631	2,346	$ 3,079
Deferred revenue		38,678		38,678		$ 38,678		34,436		$ 27,579
Genentech | Royalty
Significant agreements.
Number of years over which royalty is payable						10 years
Genentech | Maximum
Significant agreements.
Milestone payments, receivable	200,000
Genentech | Development milestone | Maximum
Significant agreements.
Milestone payments, receivable	65,000
Genentech | Regulatory milestone | Maximum
Significant agreements.
Milestone payments, receivable	$ 135,000
Genentech | Collaboration Program 1 Performance Obligation
Significant agreements.
Transaction price		4,019		4,019		$ 4,019
Genentech | Collaboration Program 2 Performance Obligation
Significant agreements.
Transaction price		8,037		8,037		$ 8,037
Genentech | Collaboration Program 3 Performance Obligation
Significant agreements.
Expansion Fee								10,000
Milestone payments, receivable			$ 1,000
Transaction price								$ 11,000
Material rights			3,500
Collaboration revenues			6,400
Genentech | Collaboration Program 3 Performance Obligation | Maximum
Significant agreements.
Period over which performance obligations will be performed						3 years
Genentech | Collaboration Program 3 Performance Obligation | Minimum
Significant agreements.
Period over which performance obligations will be performed						2 years
Genentech | Collaboration Program 4 Performance Obligation
Significant agreements.
Expansion Fee		10,000
Material rights		3,500		3,500		$ 3,500
Collaboration revenues		5,300
Deferred revenue		$ 100		100		100
Genentech | Collaboration Program 4 Performance Obligation | Maximum
Significant agreements.
Period over which performance obligations will be performed		3 years
Genentech | Collaboration Program 4 Performance Obligation | Minimum
Significant agreements.
Period over which performance obligations will be performed		2 years
Genentech | Specified Targeting Arm Material Right Arm Program One
Significant agreements.
Number of initial collaboration programs exercised | item	1
Milestone payments, receivable	$ 1,000
Option fee for development and exploitation rights	$ 1,000
Transaction price		$ 352		352		$ 352
Genentech | Two material rights associated with the LSR Go Option for Collaboration Programs One And Two
Significant agreements.
Number of collaboration programs | item	2					2
Number of expansion option collaboration programs | item						2
Transaction price		12,400		12,400		$ 12,400
Genentech | Material rights for associated and limited substitution rights
Significant agreements.
Transaction price		1,187		1,187		1,187
Deferred revenue		700	700	700		700
Genentech | Material rights associated with the LSR Go Option for Collaboration Programs Three
Significant agreements.
Deferred revenue			$ 7,400
Genentech | Material rights associated with the LSR Go Option for Collaboration Programs Four
Significant agreements.
Deferred revenue		7,400		7,400		7,400
Genentech | Two material rights for Expansion Options
Significant agreements.
Number of expansion option collaboration programs | item	2
Transaction price		$ 7,005		$ 7,005		$ 7,005
Genentech | Collaboration Program One and Two Performance Obligation
Significant agreements.
Material rights exercise period						4 years
Genentech | Collaboration Program One and Two Performance Obligation | Maximum
Significant agreements.
Regulatory, and initial commercialization milestones, payments receivable	$ 200,000
Period over which performance obligations will be performed						3 years
Genentech | Collaboration Program One and Two Performance Obligation | Minimum
Significant agreements.
Period over which performance obligations will be performed						2 years