Research Collaboration and License Agreements - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		4 Months Ended	9 Months Ended		12 Months Ended
	Nov. 30, 2017	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2015	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2018	Dec. 31, 2024	May 31, 2024	Apr. 30, 2024	Dec. 31, 2023	Jul. 31, 2021	Jun. 30, 2019	Dec. 31, 2017
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved		$ 3.7	$ 8.8		$ 3.7	$ 8.8		$ 7.8			$ 9.4
Collaboration contract asset and other assets		3.9			3.9			8.1
Contract with customer, liability		215.1	503.7		215.1	503.7		$ 448.2			549.2
Revenue, remaining performance obligation		215.1			215.1
Revenue		41.9	102.4		253.1	204.2
Operating expenses		85.7	162.7		297.0	396.2
Net loss		$ (35.1)	$ (49.2)		$ (13.4)	$ (153.8)
Basic (in dollars per share)		$ (0.48)	$ (0.68)		$ (0.18)	$ (2.14)
Diluted (in dollars per share)		$ (0.48)	$ (0.68)		$ (0.18)	$ (2.14)
Removal of Combination Trials
Research Collaboration And License Agreements [Line Items]
Revenue					$ 150.2
Operating expenses					2.6
Net loss					$ (147.6)
Basic (in dollars per share)					$ 2.02
Updated Research Timelines
Research Collaboration And License Agreements [Line Items]
Revenue					$ (2.5)
Net loss					$ (2.5)
Basic (in dollars per share)					$ 0.03
Diluted (in dollars per share)					$ 0.03
Pfizer, Inc.
Research Collaboration And License Agreements [Line Items]
Payments received							$ 28.0
Pfizer, Inc. | Collaboration Agreement
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved												$ 650.0
Collaboration agreement direct and incremental costs incurred					$ 12.9
Collaboration contract asset and other assets		$ 12.9			12.9
Pfizer, Inc. | Regulatory and Sales-Based Milestones | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved												1,400.0
Pfizer, Inc. | Regulatory Milestone Related to Marketing Approvals
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved												400.0
Pfizer, Inc. | Sales-Based Milestones
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved												$ 1,000.0
Pfizer, Inc. | Option Payments To License Agreement | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved		3.8			3.8
Pfizer, Inc. | Development Milestone Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved														$ 225.0
Pfizer, Inc. | Sales Based Milestone Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved														$ 550.0
Novartis Pharma AG | License
Research Collaboration And License Agreements [Line Items]
Revenue recognized		20.0			20.0
Contract with customer, liability									$ 150.0
Contingent payments									$ 1,010.0
Revenue, remaining performance obligation		130.0			130.0
Capitalized costs										$ 3.0
Bayer Collaboration Agreement
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved													$ 17.5
Bayer Collaboration Agreement | Development Milestone Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved													197.5
Bayer Collaboration Agreement | Sales Based Milestone Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved													$ 490.0
Bayer Collaboration Agreement | Research Funding Payments
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved											$ 12.0
Genentech
Research Collaboration And License Agreements [Line Items]
Payments received	$ 34.5			$ 11.0
Genentech | Regulatory Milestone Related to Marketing Approvals
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved		52.5			52.5
Genentech | Development Milestone Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved		44.0			44.0
Genentech | Commercial Milestones
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved		$ 60.0			$ 60.0