Related party - Gilead Sciences, Inc. - Additional Information (Details) $ / shares in Units, shares in Millions, $ in Millions			1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 27, 2023 USD ($) $ / shares shares	May 12, 2023 USD ($) Program	Oct. 31, 2022	Jan. 31, 2022 USD ($)	Jun. 30, 2023 USD ($) $ / shares	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) Program $ / shares	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($) Program shares	Dec. 31, 2020 USD ($) shares
Research and Development
Related Party Transaction [Line Items]
Reimbursed under cost-sharing provisions of arrangement					$ 34.0	$ 36.0	$ 67.0	$ 66.0
Gilead Collaboration Agreement
Related Party Transaction [Line Items]
Option payment upon completion of certain IND-enabling activities							60.0
Option payment upon achievement of certain development milestones							$ 150.0
Amended Investor Rights Agreement
Related Party Transaction [Line Items]
Lockup period			2 years
Extended lockup period			3 years
Amended Gilead Collaboration Agreement
Related Party Transaction [Line Items]
Number of programs, eligible to receive regulatory and commercial milestone payments | Program		2
Number of exercise option to programs | Program									3
Option payments received				$ 725.0
Removal of option continuation payment under agreement									$ 100.0
Option payment upon achievement of certain development milestones		$ 150.0
Gilead
Related Party Transaction [Line Items]
Percentage of outstanding common stock held					19.90%		19.90%
Gilead | Research and Development
Related Party Transaction [Line Items]
Reimbursed under cost-sharing provisions of arrangement					$ 34.0	36.0	$ 67.0	66.0
Gilead | Gilead Collaboration Agreement
Related Party Transaction [Line Items]
Collaboration term for current and future clinical programs										10 years
Option continuation payment due upon second anniversary of agreement										$ 100.0
Option continuation payment due upon fourth anniversary of agreement										100.0
Option continuation payment due upon sixth anniversary of agreement										100.0
Option Continuation Payment Due Upon Eighth Anniversary of Agreement										100.0
Upfront cash payment										175.0
Option fee per program for all other programs entering clinical development to exercise option										150.0
Number of research programs | Program							2
Revenue recognized					$ 29.0	$ 26.0	$ 54.0	$ 42.0
Gilead | Gilead Collaboration Agreement | Maximum
Related Party Transaction [Line Items]
Potential regulatory approval milestones payment receivable related to domvanalimab										$ 500.0
Gilead | Stock Purchase Agreement
Related Party Transaction [Line Items]
Percentage of premium purchase price of common stock							20.00%
Trailing days average closing price							5 days
Weighted average closing price of our common stock on grant date | $ / shares	$ 19.26				$ 33.54		$ 33.54
Issuance of common stock, shares | shares	1.0								5.7	6.0
Issuance of common stock	$ 20.0								$ 220.0
Funds received for purchase of common stock										$ 200.0
Purchase price of common stock allocation to performance obligation										$ 91.0
Gilead | Stock Purchase Agreement | Maximum
Related Party Transaction [Line Items]
Right to purchase additional outstanding voting common stock percentage					35.00%		35.00%
Gilead | Amended Gilead Collaboration Agreement
Related Party Transaction [Line Items]
Upfront cash payment		17.5					$ 35.0
Number of research programs | Program							2
Option payment upon completion of certain IND-enabling activities		45.0
Gilead | Amended Gilead Collaboration Agreement | Maximum
Related Party Transaction [Line Items]
Regulatory and commercial milestone payments received		$ 375.0