Acquisitions, Divestitures, Research Collaborations and Licensing Agreements - Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Dec. 31, 2024	Jul. 09, 2024	Dec. 31, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Goodwill	$ 21,668		$ 21,197	$ 21,204
Elanco Animal Health Incorporated Aqua Business
Business Acquisition [Line Items]
Inventories		$ 65
Property, plant and equipment		66
Other assets and liabilities, net		23
Total identifiable net assets		785
Goodwill		518
Consideration transferred		$ 1,303
Discount rate		8.50%
Elanco Animal Health Incorporated Aqua Business | Product Rights - Clynay
Business Acquisition [Line Items]
Product rights and other		$ 340
Estimated useful life of intangible assets		15 years
Elanco Animal Health Incorporated Aqua Business | Other Product Rights
Business Acquisition [Line Items]
Product rights and other		$ 291
Estimated useful life of intangible assets		15 years