Revenue - Revenue by Species (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from External Customer [Line Items]
Revenues	$ 6,675	$ 6,260	$ 5,825
Cattle
Revenue from External Customer [Line Items]
Revenues	1,558	1,654	1,754
Swine
Revenue from External Customer [Line Items]
Revenues	621	611	663
Poultry
Revenue from External Customer [Line Items]
Revenues	537	559	522
Fish
Revenue from External Customer [Line Items]
Revenues	148	134	132
Other
Revenue from External Customer [Line Items]
Revenues	76	72	83
Livestock
Revenue from External Customer [Line Items]
Revenues	2,940	3,030	3,154
Dogs and Cats
Revenue from External Customer [Line Items]
Revenues	215	195	168
Horses
Revenue from External Customer [Line Items]
Revenues	3,437	2,950	2,445
Companion Animal
Revenue from External Customer [Line Items]
Revenues	3,652	3,145	2,613
Contract Manufacturing and Human Health Diagnostics [Member]
Revenue from External Customer [Line Items]
Revenues	$ 83	$ 85	$ 58