Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2026

Fair Value Disclosures [Abstract]

Summary of assets and liabilities recorded at fair value

The tables below present information about our assets and liabilities that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques we utilized to determine such fair value:

	Fair Value Measurements on a Recurring Basis
	As of March 31, 2026
(In millions)	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	2,512.8	$	—	$	2,512.8	$	—
Marketable debt securities:
Corporate debt securities	734.2		—		734.2		—
Government securities	547.3				547.3		—
Mortgage and other asset backed securities	84.1				84.1		—
Marketable equity securities	137.4		137.4		—		—
Other current assets:
Derivative contracts	19.1		—		19.1		—
Other non-current assets:
Convertible note(1)	35.0		—		—		35.0
Plan assets for deferred compensation	56.8		—		56.8		—
Derivative contracts	5.9		—		5.9		—
Total	$	4,132.6	$	137.4	$	3,960.2	$	35.0
Liabilities:
Other current liabilities:
Derivative contracts	$	38.2	$	—	$	38.2	$	—
Other non-current liabilities:
Contingent consideration obligations	266.9		—		—		266.9
Total	$	305.1	$	—	$	38.2	$	266.9

(1) Convertible notes includes a $30.0 million convertible note we invested in as part of our strategic research arrangement with City Therapeutics during 2025, as well as a $5.0 million convertible note we invested into Neela Therapeutics, Inc. during 2025. We elected the fair value option for both convertible notes. For additional information on the arrangement with City Therapeutics, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in our 2025 Form 10-K.

	Fair Value Measurements on a Recurring Basis
	As of December 31, 2025
(In millions)	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	2,233.2	$	—	$	2,233.2	$	—
Marketable debt securities:
Corporate debt securities	537.6		—		537.6		—
Government securities	648.8		—		648.8		—
Mortgage and other asset backed securities	52.7		—		52.7		—
Marketable equity securities	118.1		118.1		—		—
Other current assets:
Derivative contracts	10.0		—		10.0		—
Other non-current assets:
Convertible notes(1)	35.0		—		—		35.0
Plan assets for deferred compensation	52.2		—		52.2		—
Derivative contracts	0.4		—		0.4		—
Total	$	3,688.0	$	118.1	$	3,534.9	$	35.0
Liabilities:
Other current liabilities:
Derivative contracts	$	56.7	$	—	$	56.7	$	—
Other non-current liabilities:
Derivative contracts	2.2		—		2.2		—
Contingent consideration obligations	246.4		—		—		246.4
Total	$	305.3	$	—	$	58.9	$	246.4

(1) Convertible notes includes a $30.0 million convertible note we invested in as part of our strategic research arrangement with City Therapeutics during 2025, as well as a $5.0 million convertible note we invested into Neela Therapeutics, Inc. during 2025. We elected the fair value option for both convertible notes. For additional information on the arrangement with City Therapeutics, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in our 2025 Form 10-K.

Fair Value Measurement Inputs and Valuation Techniques

The following tables present quantitative information, as of the dates indicated, about the valuation techniques and significant unobservable inputs used in the valuation of our Level 3 financial assets and liabilities measured at fair value on a recurring basis:

	Quantitative Information about Level 3 Fair Value Measurements
	As of March 31, 2026
(In millions)	Fair Value		Valuation Technique	Significant Unobservable Input(s)	Range	Weighted Average
Liabilities:
Contingent consideration obligations	$	266.9	Discounted cash flow	Discount rate	5.7%	5.7%
				Expected timing of achievement of development milestones	2028	—

	Quantitative Information about Level 3 Fair Value Measurements
	As of December 31, 2025
(In millions)	Fair Value		Valuation Technique	Significant Unobservable Input(s)	Range	Weighted Average
Liabilities:
Contingent consideration obligations	$	246.4	Discounted cash flow	Discount rate	5.3% - 5.4%	5.4%
				Expected timing of achievement of development milestones	2028 - 2030	—

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation

The following table provides a roll forward of the fair value of our contingent consideration obligations, which were classified as Level 3 measurements:

	For the Three Months Ended March 31,
(In millions)	2026		2025
Fair value, beginning of period	$	246.4	$	512.8
Changes in fair value	20.5		9.6
Fair value, end of period	$	266.9	$	522.4

Summary of fair and carrying value of debt instruments

The fair and carrying values of our debt instruments, which are Level 2 liabilities, are summarized as follows:

	As of March 31, 2026				As of December 31, 2025
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Non-current portion:
2.250% Senior Notes due May 1, 2030	$	1,369.5	$	1,495.9	$	1,378.7	$	1,495.7
5.050% Senior Notes due January 15, 2031	407.5		398.1		413.0		398.0
5.750% Senior Notes due May 15, 2035	672.5		645.6		684.5		645.5
5.200% Senior Notes due September 15, 2045	1,004.8		1,101.6		1,029.5		1,101.5
3.150% Senior Notes due May 1, 2050	943.9		1,475.8		973.0		1,475.6
3.250% Senior Notes due February 15, 2051	443.6		481.3		461.8		480.3
6.450% Senior Notes due May 15, 2055	725.9		690.2		737.6		690.2
Non-current portion of notes payable	5,567.7		6,288.5		5,678.1		6,286.8
Total notes payable	$	5,567.7	$	6,288.5	$	5,678.1	$	6,286.8