Revenue - Revenue by Major Species (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Revenue from External Customer [Line Items]
Revenue		$ 2,460	$ 2,361	$ 4,680	$ 4,551
Companion animal
Revenue from External Customer [Line Items]
Revenue		1,788	1,649	3,334	3,099
Companion animal | U.S.
Revenue from External Customer [Line Items]
Revenue		1,176	1,080	2,149	1,978
Companion animal | International
Revenue from External Customer [Line Items]
Revenue		612	569	1,185	1,121
Livestock
Revenue from External Customer [Line Items]
Revenue		638	694	1,283	1,414
Livestock | U.S.
Revenue from External Customer [Line Items]
Revenue		180	228	390	493
Livestock | International
Revenue from External Customer [Line Items]
Revenue		458	466	893	921
Contract manufacturing & human health
Revenue from External Customer [Line Items]
Revenue		34	18	63	38
Operating Segments | U.S.
Revenue from External Customer [Line Items]
Revenue		1,356	1,308	2,539	2,471
Operating Segments | International
Revenue from External Customer [Line Items]
Revenue	[1]	$ 1,070	$ 1,035	$ 2,078	$ 2,042

[1] Revenue denominated in euros was $468 million and $460 million for the six months ended June 30, 2025 and 2024, respectively.