Segment and Other Revenue Information - Revenue by Species (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 02, 2017	Apr. 03, 2016
Revenue from External Customer [Line Items]
Revenue	$ 1,231	$ 1,162
Livestock:
Revenue from External Customer [Line Items]
Revenue	703	683
Cattle
Revenue from External Customer [Line Items]
Revenue	386	377
Swine
Revenue from External Customer [Line Items]
Revenue	160	146
Poultry
Revenue from External Customer [Line Items]
Revenue	116	122
Fish
Revenue from External Customer [Line Items]
Revenue	21	17
Other
Revenue from External Customer [Line Items]
Revenue	20	21
Companion Animal:
Revenue from External Customer [Line Items]
Revenue	517	466
Horses
Revenue from External Customer [Line Items]
Revenue	35	39
Dogs and Cats
Revenue from External Customer [Line Items]
Revenue	482	427
Contract Manufacturing
Revenue from External Customer [Line Items]
Revenue	$ 11	$ 13