Revenue - Revenue by Major Species (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenue from External Customer [Line Items]
Revenue		$ 2,400	$ 2,388	$ 7,080	$ 6,939
Companion animal
Revenue from External Customer [Line Items]
Revenue		1,652	1,609	4,986	4,708
Companion animal | U.S.
Revenue from External Customer [Line Items]
Revenue		1,069	1,068	3,218	3,046
Companion animal | International
Revenue from External Customer [Line Items]
Revenue		583	541	1,768	1,662
Livestock
Revenue from External Customer [Line Items]
Revenue		725	758	2,008	2,172
Livestock | U.S.
Revenue from External Customer [Line Items]
Revenue		253	278	643	771
Livestock | International
Revenue from External Customer [Line Items]
Revenue		472	480	1,365	1,401
Contract manufacturing & human health
Revenue from External Customer [Line Items]
Revenue		23	21	86	59
Operating Segments | U.S.
Revenue from External Customer [Line Items]
Revenue		1,322	1,346	3,861	3,817
Operating Segments | International
Revenue from External Customer [Line Items]
Revenue	[1]	$ 1,055	$ 1,021	$ 3,133	$ 3,063

[1] Revenue denominated in euros was $720 million and $694 million for the nine months ended September 30, 2025 and 2024, respectively.