v3.26.3
Research Collaboration and License Agreements - Additional Information (Details)
$ / shares in Units, $ in Millions
 1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
May 11, 2026
USD ($)
May 31, 2026
USD ($)
Nov. 30, 2017
USD ($)
Sep. 30, 2026
USD ($)
$ / shares
Jun. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
$ / shares
Sep. 30, 2026
USD ($)
$ / shares
Sep. 30, 2025
USD ($)
$ / shares
Dec. 31, 2018
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
May 31, 2024
USD ($)
Jul. 31, 2021
USD ($)
Dec. 31, 2017
USD ($)
Research Collaboration And License Agreements [Line Items]                              
Revenue       $ 0.5   $ 41.9 $ 265.8 $ 253.1              
Contract revenue receivable if milestones achieved       22.6   0.0 22.6 0.0     $ 0.0 $ 0.0      
Contract and other assets       8.5     8.5       3.8        
General and administrative       12.6   21.0 55.7 72.9              
Revenue recognized             152.9 233.1              
Collaboration settlement liability       46.4   0.0 46.4 0.0     0.0 0.0      
Contract with customer, liability       0.0   215.1 0.0 215.1     $ 205.6 $ 448.2      
Operating expenses       59.6   85.7 224.6 297.0              
Net loss       $ (53.9)   $ (35.1) $ 57.9 $ (13.4)              
Net loss per common share, basic (in dollars per share) | $ / shares       $ 0.82   $ 0.48 $ (0.89) $ 0.18              
Net loss per common share, basic (in dollars per share) | $ / shares       $ 0.82   $ 0.48 $ (0.88) $ 0.18              
Removal of Combination Trials                              
Research Collaboration And License Agreements [Line Items]                              
Revenue               $ 150.2              
Operating expenses               2.6              
Net loss               $ (147.6)              
Net loss per common share, basic (in dollars per share) | $ / shares               $ 2.02              
Net loss per common share, basic (in dollars per share) | $ / shares               $ 2.02              
Updated Research Timelines                              
Research Collaboration And License Agreements [Line Items]                              
Revenue               $ (2.5)              
Net loss               $ (2.5)              
Net loss per common share, basic (in dollars per share) | $ / shares               $ 0.03              
Net loss per common share, basic (in dollars per share) | $ / shares               $ 0.03              
Rigel Pharmaceuticals, Inc. | License revenue                              
Research Collaboration And License Agreements [Line Items]                              
Development activities $ 40.0                            
Revenue       $ 0.5   $ 0.0 $ 63.0 $ 0.0              
Upfront license payment 70.0                            
Contract revenue receivable if milestones achieved 15.0                            
Consideration payable 42.5                            
Rigel Pharmaceuticals, Inc. | License revenue | Maximum                              
Research Collaboration And License Agreements [Line Items]                              
Contingent payments $ 320.0                            
Rigel Pharmaceuticals, Inc. | License Agreement, Reimbursement Fees                              
Research Collaboration And License Agreements [Line Items]                              
Development activities, percentage to refund 0.50                            
Revenue $ 20.0           20.0                
Rigel Pharmaceuticals, Inc. | License Agreement, Sales-Based Royalties                              
Research Collaboration And License Agreements [Line Items]                              
Revenue       0.5     0.5                
Rigel Pharmaceuticals, Inc. | License Agreement, Excluding Cost Reimbursement Fees                              
Research Collaboration And License Agreements [Line Items]                              
Revenue $ 42.5                            
Pfizer, Inc.                              
Research Collaboration And License Agreements [Line Items]                              
Payments received                 $ 28.0            
Pfizer, Inc. | Collaboration Agreement                              
Research Collaboration And License Agreements [Line Items]                              
Revenue         $ 126.4                    
Contract revenue receivable if milestones achieved                           $ 650.0  
Collaboration agreement direct and incremental costs incurred             12.9                
Contract and other assets       12.9     12.9                
General and administrative             3.1                
Revenue recognized   $ 179.1   0.0     21.7                
Collaboration settlement liability   $ 52.7                          
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. | Pfizer Collaboration Agreement                              
Research Collaboration And License Agreements [Line Items]                              
Revenue recognized             3.5                
Pfizer, Inc. | Maximum | Regulatory and Sales-Based Milestones                              
Research Collaboration And License Agreements [Line Items]                              
Contract revenue receivable if milestones achieved                           $ 1,400.0  
Pfizer, Inc. | Maximum | Option Payments To License Agreement                              
Research Collaboration And License Agreements [Line Items]                              
Contract revenue receivable if milestones achieved                             $ 3.8
Pfizer, Inc. | Maximum | Development Milestone Payments                              
Research Collaboration And License Agreements [Line Items]                              
Contract revenue receivable if milestones achieved                             225.0
Pfizer, Inc. | Maximum | Sales Based Milestone Payments                              
Research Collaboration And License Agreements [Line Items]                              
Contract revenue receivable if milestones achieved                             $ 550.0
Vepdegestrant | Milestone Revenue                              
Research Collaboration And License Agreements [Line Items]                              
Revenue       0.0 $ 50.0 0.0 50.0 0.0              
Novartis Pharma AG | License revenue                              
Research Collaboration And License Agreements [Line Items]                              
Revenue       $ 0.0   $ 20.0 $ 0.0 $ 20.0              
Contract with customer, liability                         $ 150.0    
Contingent payments                         $ 1,010.0    
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                        
Genentech | Commercial Milestones                              
Research Collaboration And License Agreements [Line Items]                              
Contract revenue receivable if milestones achieved     60.0                        
Genentech | Maximum | Development Milestone Payments                              
Research Collaboration And License Agreements [Line Items]                              
Contract revenue receivable if milestones achieved     $ 44.0