Collaborative and Other Relationships - Summary of Activity Related to the UCB Collaboration (Details) - Income Statement Location [Axis]: us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost - UCB Pharma S.A. - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Collaborative arrangements and non-collaborative arrangement transactions | ||||
| Expense incurred by the collaboration | $ 38.4 | $ 23.2 | $ 97.1 | $ 62.8 |
| Expense reflected within statements of income | $ 19.2 | $ 11.6 | $ 48.5 | $ 31.4 |