Research and Development Funding Expense	12 Months Ended
Dec. 31, 2025
Research and Development [Abstract]
Research and Development Funding Expense	Research and Development Funding Expense R&D funding expense consists of certain development-stage funding payments that we have made to counterparties to acquire royalties or milestones on product candidates. The payments can be made upfront as milestones upon the achievement of certain predefined criteria, or over time as the related product candidates undergo clinical trials. In the first quarter of 2025, we entered into an R&D funding arrangement with Biogen to provide $250 million over six quarters, including $50 million upfront for the development of litifilimab. We did not enter into any new ongoing R&D funding arrangements in 2024 or 2023. We recognized R&D funding expense of $452.0 million, $2.0 million and $52.0 million in 2025, 2024 and 2023, respectively. The R&D expense in 2025 is primarily related to an upfront payment of $250.0 million to acquire royalties on daraxonrasib and the R&D funding arrangement for litifilimab. The R&D expense in 2024 related to ongoing development-stage funding payments. The R&D expense in 2023 primarily related to a $50.0 million clinical milestone payment to Cytokinetics for Myqorzo, formerly known as aficamten. As of December 31, 2025, we had an unfunded commitment of $50 million related to the R&D funding arrangement with Biogen for litifilimab.

R&D funding expense consists of certain development-stage funding payments that we have made to counterparties to acquire royalties or milestones on product candidates. The payments can be made upfront as milestones upon the achievement of certain predefined criteria, or over time as the related product candidates undergo clinical trials. In the first quarter of 2025, we entered into an R&D funding arrangement with Biogen to provide $250 million over six quarters, including $50 million upfront for the development of litifilimab. We did not enter into any new ongoing R&D funding arrangements in 2024 or 2023.

We recognized R&D funding expense of $452.0 million, $2.0 million and $52.0 million in 2025, 2024 and 2023, respectively. The R&D expense in 2025 is primarily related to an upfront payment of $250.0 million to acquire royalties on daraxonrasib and the R&D funding arrangement for litifilimab. The R&D expense in 2024 related to ongoing development-stage funding payments. The R&D expense in 2023 primarily related to a $50.0 million clinical milestone payment to Cytokinetics for Myqorzo, formerly known as aficamten.

As of December 31, 2025, we had an unfunded commitment of $50 million related to the R&D funding arrangement with Biogen for litifilimab.