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Agreement Termination By Counterparty, Minimal Contractual Time

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Agreement Termination, Contractual Time Threshold

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Board Of Directors Maximum Duration Term

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Number Of Gene Therapy Programs

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Number Of Non-clinical Stage Compound

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Number Of Preclinical Candidates

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Number Of Undisclosed Programs

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Term of the patent, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The amount of potential milestone payments to be paid under a license agreement.

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The number of shares sold by the collaboration partner per stock transaction.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

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Amount of writeoff for research and development asset acquired in transaction other than business combination or from joint venture formation or both.

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Amount of expense for research and development. Includes, but is not limited to, cost for computer software product to be sold, leased, or otherwise marketed and writeoff of research and development assets acquired in transaction other than business combination or joint venture formation or both. Excludes write-down of intangible asset acquired in business combination or from joint venture formation or both, used in research and development activity.

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Collaboration and License Agreements (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) undisclosedProgram preclinicalCandidate geneTherapyProgram non-clinicalStageCompound	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 $ / shares shares	Dec. 31, 2019 $ / shares shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Acquired in-process research and development	$ 17.4	$ 12.5	$ 143.9
Collaborative Arrangement \| Common Stock \| Voyager
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Beneficial ownership			19.90%
Nxera Pharma UK Limited \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	15.0	50.0
Potential milestone payments	$ 2,500.0
Agreement termination, contractual time threshold	90 days
Agreement termination by counterparty, contractual time threshold	365 days
Agreement termination by counterparty, minimal contractual time	120 days
Takeda \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	$ 37.5	7.5
Potential milestone payments	$ 740.0
Agreement termination, contractual time threshold	12 months
Number of non-clinical stage compounds \| non-clinicalStageCompound	3
Agreement termination, minimal contractual time	6 months
Xenon \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	$ 7.5
Potential milestone payments	$ 1,700.0
Agreement termination, contractual time threshold	90 days
Number of preclinical candidates \| preclinicalCandidate	3
Sale of stock (in shares) \| shares				300,000	300,000	1,400,000
Share price (in USD per share) \| $ / shares				$ 31.855	$ 19.9755	$ 14.196
2019 Voyager Agreement \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development		5.0
Potential milestone payments	$ 470.0
Agreement termination, contractual time threshold	1 year
Agreement termination, minimal contractual time	180 days
Share price (in USD per share) \| $ / shares						$ 11.9625
Number of undisclosed programs \| undisclosedProgram	2
2019 Voyager Agreement \| Collaborative Arrangement \| Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock (in shares) \| shares						4,200,000
2023 Voyager Agreement \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	$ 3.0	6.0
Potential milestone payments	$ 6,100.0
Agreement termination, contractual time threshold	1 year
Agreement termination, minimal contractual time	180 days
Share price (in USD per share) \| $ / shares			$ 8.88
Number of gene therapy programs \| geneTherapyProgram	3
Upfront payments made			$ 175.0
Board of directors maximum duration term			10 years
Equity securities cost			$ 31.3
Acquired in-process research and development			$ 143.9
2023 Voyager Agreement \| Collaborative Arrangement \| Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock (in shares) \| shares			4,400,000
Sanofi S.A \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development		$ 5.0
Potential milestone payments	$ 10.0
Sanofi S.A \| Collaborative Arrangement \| Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalties at tiered percentage	3.00%
Sanofi S.A \| Collaborative Arrangement \| Minimum \| Patents
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Patent term	16 years
Sanofi S.A \| Collaborative Arrangement \| Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalties at tiered percentage	5.00%