Financial Instruments - Information About Changes in Liabilities for Contingent Consideration (Details) $ in Millions	3 Months Ended
Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 354	$ 456
Changes in estimated fair value	(2)	14
Payments	(126)	(117)
Fair value, ending balance	226	$ 353
Sanofi Pasteur
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Current liability	$ 133
Contingent consideration, measurement input, discount rate	0.115

Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
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-Paragraph 4
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479581/805-30-50-4

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- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
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-Name Accounting Standards Codification
-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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-SubTopic 30
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- Definition

Value of input used to measure contingent consideration liability from business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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