Acquisition, License Agreement and Research and Development Funding Collaboration Agreement - Narrative (Details) - USD ($)		1 Months Ended			12 Months Ended			24 Months Ended	115 Months Ended
		Jan. 31, 2024	May 31, 2018	Jun. 30, 2016	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2025	Dec. 31, 2025
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense due to cost share payments to related party	[1]				$ 418,778,000	$ 396,440,000	$ 423,876,000
Reduction to research and development expense					18,000,000.0	10,900,000
Deferred research and development funding liability, current					21,100,000	14,100,000		$ 21,100,000	$ 21,100,000
Collaboration And Development Funding Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate payments								$ 50,000,000.0
Collaborative agreement, aggregate consideration amount		$ 75,000,000.0
Genentech | Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense due to cost share payments to related party					0	0	0
Genentech | Research and development | Genetech License Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate payments									$ 25,000,000.0
Genentech | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments upon achievement of specified clinical and regulatory milestones				$ 315,000,000.0
Regulatory | Genentech
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments upon achievement of specified clinical and regulatory milestones				102,500,000
Commercial | Genentech
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments upon achievement of specified clinical and regulatory milestones				175,000,000.0
Clinical | Genentech
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments upon achievement of specified clinical and regulatory milestones				$ 37,500,000
Collaborative Arrangement with F-Star and Acquisition of F-Star Gamma | Exercise of buy-out option
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contingent payments upon achievement of milestones			$ 210,000,000.0
Collaborative Arrangement with F-Star and Acquisition of F-Star Gamma | Contingent Payments Upon Achievement of Specialized Clinical Milestone
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contingent consideration payment triggered							$ 30,000,000.0
Contingent consideration amount recognized					$ 0	$ 0
Collaborative Arrangement with F-Star and Acquisition of F-Star Gamma | Regulatory | Exercise of buy-out option
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contingent payments upon achievement of milestones			60,000,000.0
Collaborative Arrangement with F-Star and Acquisition of F-Star Gamma | Regulatory | Exercise of buy-out option | Tividenofusp Alfa
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contingent payments upon achievement of milestones			36,000,000.0
Collaborative Arrangement with F-Star and Acquisition of F-Star Gamma | Commercial | Exercise of buy-out option
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contingent payments upon achievement of milestones			$ 150,000,000.0

[1] Includes expense for cost sharing payments to a related party of $17.7 million for the year ended December 31, 2023.