Significant agreements - Genentech Collaboration Agreement (Details) $ in Thousands		1 Months Ended			12 Months Ended
	Feb. 21, 2020 USD ($) item	Dec. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Nov. 30, 2021 USD ($)	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Oct. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)
Significant agreements.
Collaboration revenues					$ 14,463	$ 11,697	$ 10,390
Deferred revenue		$ 61,873			61,873	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
Collaboration revenues					3,565	5,660	4,896
Deferred revenue		39,308			$ 39,308	$ 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
Genentech | Collaboration Program 2 Performance Obligation
Significant agreements.
Transaction price		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		8,400
Amount of estimate of variable consideration		$ 2,000
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
Collaboration revenues			5,300
Deferred revenue			$ 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
Option fee for development and exploitation rights	$ 1,000
Milestone payments, receivable	$ 1,000
Transaction price		$ 352			352
Genentech | Material rights for associated and limited substitution rights
Significant agreements.
Transaction price		1,187			1,187
Deferred revenue		700	$ 700		$ 700
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
Transaction price		12,400			$ 12,400
Genentech | Material rights associated with the LSR Go Option for Collaboration Programs Three
Significant agreements.
Deferred revenue		7,400			$ 7,400
Genentech | Material rights associated with the LSR Go Option for Collaboration Programs Four
Significant agreements.
Deferred revenue			$ 7,400
Genentech | Two material rights for Expansion Options
Significant agreements.
Number of expansion option collaboration programs | item	2				2
Transaction price		$ 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