Revenue - Revenue by Product (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from External Customer [Line Items]
Revenue	$ 1,534	$ 1,455
Vaccines
Revenue from External Customer [Line Items]
Revenue	349	358
Other pharmaceuticals
Revenue from External Customer [Line Items]
Revenue	197	190
Anti-infectives
Revenue from External Customer [Line Items]
Revenue	280	286
Parasiticides
Revenue from External Customer [Line Items]
Revenue	255	231
Medicated feed additives
Revenue from External Customer [Line Items]
Revenue	125	112
Animal health diagnostics
Revenue from External Customer [Line Items]
Revenue	60	60
Other non-pharmaceuticals
Revenue from External Customer [Line Items]
Revenue	51	40
Total products and services
Revenue from External Customer [Line Items]
Revenue	1,514	1,436
Dermatology
Revenue from External Customer [Line Items]
Revenue	197	159
Cattle
Revenue from External Customer [Line Items]
Revenue	$ 370	$ 380