Segment and Other Revenue Information - Revenue by Major Product Category (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 03, 2016	Mar. 29, 2015
Revenue from External Customer [Line Items]
Revenue	$ 1,162	$ 1,102
Anti-infectives
Revenue from External Customer [Line Items]
Revenue	291	312
Vaccines
Revenue from External Customer [Line Items]
Revenue	301	271
Parasiticides
Revenue from External Customer [Line Items]
Revenue	145	153
Medicated feed additives
Revenue from External Customer [Line Items]
Revenue	138	121
Other pharmaceuticals
Revenue from External Customer [Line Items]
Revenue	221	187
Other non-pharmaceuticals
Revenue from External Customer [Line Items]
Revenue	53	48
Contract manufacturing
Revenue from External Customer [Line Items]
Revenue	$ 13	$ 10