v3.26.3
Fair Value of Financial Instruments - Fair Value of Financial Instruments (Detail) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Milestone Rights | Fair Value, Inputs, Level 3    
Financial liabilities:    
Total financial liabilities fair value $ 17.4  
Financing Liability | Fair Value, Inputs, Level 3    
Financial liabilities:    
Total financial liabilities fair value 101.2  
Liability for Sale of Future Royalties | Fair Value, Inputs, Level 3    
Financial liabilities:    
Total financial liabilities fair value 89.6  
Carrying Amount | Senior Convertible Notes    
Financial liabilities:    
Total financial liabilities fair value   $ 36.3
Carrying Amount | Milestone Rights    
Financial liabilities:    
Total financial liabilities fair value 2.0 2.5
Carrying Amount | Financing Liability    
Financial liabilities:    
Total financial liabilities fair value 102.8 103.4
Carrying Amount | Liability for Sale of Future Royalties    
Financial liabilities:    
Total financial liabilities fair value $ 144.6 151.3
Carrying Amount | Contingent Milestone Liability    
Financial liabilities:    
Total financial liabilities fair value   26.2
Estimate of Fair Value Measurement | Senior Convertible Notes | Fair Value, Inputs, Level 3    
Financial liabilities:    
Total financial liabilities fair value   39.3
Estimate of Fair Value Measurement | Milestone Rights | Fair Value, Inputs, Level 3    
Financial liabilities:    
Total financial liabilities fair value   22.0
Estimate of Fair Value Measurement | Financing Liability | Fair Value, Inputs, Level 3    
Financial liabilities:    
Total financial liabilities fair value   121.9
Estimate of Fair Value Measurement | Liability for Sale of Future Royalties | Fair Value, Inputs, Level 3    
Financial liabilities:    
Total financial liabilities fair value   168.1
Estimate of Fair Value Measurement | Contingent Milestone Liability | Fair Value, Inputs, Level 3    
Financial liabilities:    
Total financial liabilities fair value   $ 26.2