Significant agreements - Genentech Collaboration Agreement (Details) $ in Thousands				1 Months Ended			3 Months Ended		12 Months Ended
	Mar. 27, 2023 USD ($)	Jul. 09, 2021 USD ($)	Feb. 21, 2020 USD ($) item	Dec. 31, 2022 USD ($)	Nov. 30, 2021 USD ($)	May 31, 2018 USD ($)	Mar. 31, 2023 USD ($) item	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2021 USD ($)	Oct. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)
Significant agreements.
Deferred revenue				$ 61,873			$ 108,721		$ 61,873		$ 71,340
Collaboration revenues							4,896	$ 3,860
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
Deferred revenue				39,308			38,025	38,000	39,308		34,436
Collaboration revenues							2,112	1,474
Genentech | Deferred revenue material rights option
Significant agreements.
Deferred revenue							$ 27,900
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
Genentech | Collaboration Program 2 Performance Obligation
Significant agreements.
Transaction price							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
Amount of estimate of variable consideration				2,000
Collaboration revenues				$ 8,400
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.
Transaction price				$ 10,000					10,000
Deferred revenue				100					100
Material rights				3,500					3,500
Collaboration revenues									5,300
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
Genentech | Material rights for associated and limited substitution rights
Significant agreements.
Transaction price							$ 1,187
Deferred revenue				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
Number of expansion option collaboration programs | item							2
Transaction price							$ 12,400
Genentech | Material rights associated with the LSR Go Option for Collaboration Programs One
Significant agreements.
Deferred revenue										$ 6,200
Genentech | Material rights associated with the LSR Go Option for Collaboration Programs Three
Significant agreements.
Deferred revenue				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
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
Ionis
Significant agreements.
Upfront cash payment		$ 31,000
Number of years over which royalty is payable		10 years
Transaction price		$ 38,000					$ 38,000
Period over which performance obligations will be performed							3 years
Material rights exercise period							4 years
Deferred revenue				21,489			$ 19,130		21,489		34,115
Collaboration revenues							2,784	2,314
Ionis | Deferred revenue material rights option
Significant agreements.
Deferred revenue							3,500
Novartis Collaboration Agreement
Significant agreements.
Upfront cash payment	$ 50,000
Milestone payments, receivable	840,000
Transaction price	$ 50,000
Period over which performance obligations will be performed	3 years
Material rights exercise period	6 years
Deferred revenue				0			50,467		0
Collaboration revenues							0	$ 0
Novartis Collaboration Agreement | Deferred revenue material rights option
Significant agreements.
Deferred revenue							32,300
AstraZeneca
Significant agreements.
Option fee for development and exploitation rights						$ 5,000
Transaction price						$ 5,700
Deferred revenue				$ 1,076			1,099		$ 1,076		$ 2,361
Collaboration revenues							0
AstraZeneca | Target 4 and Target 5 Material Rights
Significant agreements.
Deferred revenue							$ 1,100