Fair Value of Financial Instruments - Fair Value of Financial Instruments (Detail) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Carrying Amount \| Senior Convertible Notes
Financial liabilities:
Total financial liabilities fair value	$ 36.2	$ 36.1
Carrying Amount \| Milestone Rights
Financial liabilities:
Total financial liabilities fair value	2.5	3.2
Carrying Amount \| Financing Liability
Financial liabilities:
Total financial liabilities fair value	103.7	103.9
Carrying Amount \| Liability for Sale of Future Royalties
Financial liabilities:
Total financial liabilities fair value	150.6	149.6
Estimate of Fair Value Measurement \| Senior Convertible Notes \| Fair Value, Inputs, Level 3
Financial liabilities:
Total financial liabilities fair value	36.0	46.9
Estimate of Fair Value Measurement \| Milestone Rights \| Fair Value, Inputs, Level 3
Financial liabilities:
Total financial liabilities fair value	16.5	19.2
Estimate of Fair Value Measurement \| Financing Liability \| Fair Value, Inputs, Level 3
Financial liabilities:
Total financial liabilities fair value	116.8	117.4
Estimate of Fair Value Measurement \| Liability for Sale of Future Royalties \| Fair Value, Inputs, Level 3
Financial liabilities:
Total financial liabilities fair value	$ 157.8	$ 156.7

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.