Segment and Other Revenue Information - Revenue by Major Product Category (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 02, 2017	Apr. 03, 2016
Revenue from External Customer [Line Items]
Revenue	$ 1,231	$ 1,162
Anti-infectives
Revenue from External Customer [Line Items]
Revenue	268	291
Vaccines
Revenue from External Customer [Line Items]
Revenue	319	301
Parasiticides
Revenue from External Customer [Line Items]
Revenue	184	145
Medicated feed additives
Revenue from External Customer [Line Items]
Revenue	123	138
Other pharmaceuticals
Revenue from External Customer [Line Items]
Revenue	272	221
Other non-pharmaceuticals
Revenue from External Customer [Line Items]
Revenue	54	53
Contract manufacturing
Revenue from External Customer [Line Items]
Revenue	$ 11	$ 13