Revenue - Revenue by 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
Dogs and Cats
Revenue from External Customer [Line Items]
Revenue	1,586	1,551	4,783	4,516
Horses
Revenue from External Customer [Line Items]
Revenue	66	58	203	192
Livestock
Revenue from External Customer [Line Items]
Revenue	725	758	2,008	2,172
Cattle
Revenue from External Customer [Line Items]
Revenue	399	391	1,077	1,132
Swine
Revenue from External Customer [Line Items]
Revenue	111	131	341	388
Poultry
Revenue from External Customer [Line Items]
Revenue	106	139	315	410
Fish
Revenue from External Customer [Line Items]
Revenue	78	70	205	177
Sheep and other
Revenue from External Customer [Line Items]
Revenue	31	27	70	65
Contract manufacturing & human health
Revenue from External Customer [Line Items]
Revenue	$ 23	$ 21	$ 86	$ 59