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Collaborative and Other Relationships - Summary of Activity Related to the UCB Collaboration (Details) - Research and development - UCB Pharma S.A. - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Collaborative arrangements and non-collaborative arrangement transactions |  |  |  |
Expense incurred by the collaboration | $ 17.8 | $ 16.5 | $ 39.6 | $ 33.1
Expense reflected within statements of income | $ 8.9 | $ 8.3 | $ 19.8 | $ 16.6

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