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Segment Information - Schedule of Significant Expenses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Segment Reporting Information [Line Items]
Research and development	$ 1,327.4	$ 1,248.4
Reportable Segment
Segment Reporting Information [Line Items]
Research and development	1,327.4	1,248.4
Reimbursement of research and development expenses by collaborators	(37.3)	(43.8)
Reportable Segment | Clinical manufacturing costs
Segment Reporting Information [Line Items]
Research and development	310.3	274.5
Reportable Segment | Direct research and development expenses
Segment Reporting Information [Line Items]
Research and development	388.4	408.3
Reportable Segment | Indirect research and development expenses:
Segment Reporting Information [Line Items]
Research and development	666.0	609.4
Reportable Segment | Indirect research and development expenses: | Payroll and benefits
Segment Reporting Information [Line Items]
Research and development	451.6	418.9
Reportable Segment | Indirect research and development expenses: | Lab supplies and other research and development costs
Segment Reporting Information [Line Items]
Research and development	60.0	55.9
Reportable Segment | Indirect research and development expenses: | Occupancy and other operating costs
Segment Reporting Information [Line Items]
Research and development	$ 154.4	$ 134.6

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- Definition

Research And Development Expense, Reimbursements

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
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-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-Publisher FASB
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