Segment and Other Revenue Information - Revenue by Species (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Revenue from External Customer [Line Items]
Revenue	$ 1,175	$ 1,158	$ 2,277	$ 2,255
Livestock [Member]
Revenue from External Customer [Line Items]
Revenue	690	703	1,405	1,409
Cattle [Member]
Revenue from External Customer [Line Items]
Revenue	372	379	769	770
Swine [Member]
Revenue from External Customer [Line Items]
Revenue	162	157	332	317
Poultry [Member]
Revenue from External Customer [Line Items]
Revenue	138	146	267	281
Other [Member]
Revenue from External Customer [Line Items]
Revenue	18	21	37	41
Companion Animal [Member]
Revenue from External Customer [Line Items]
Revenue	471	439	848	819
Horses [Member]
Revenue from External Customer [Line Items]
Revenue	42	46	82	89
Dogs and Cats [Member]
Revenue from External Customer [Line Items]
Revenue	429	393	766	730
Contract Manufacturing [Member]
Revenue from External Customer [Line Items]
Revenue	$ 14	$ 16	$ 24	$ 27