Segment and Other Revenue Information - Revenue by Species (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2016	Sep. 27, 2015	Oct. 02, 2016	Sep. 27, 2015
Revenue from External Customer [Line Items]
Revenue	$ 1,241	$ 1,214	$ 3,611	$ 3,491
Livestock:
Revenue from External Customer [Line Items]
Revenue	735	750	2,091	2,155
Cattle
Revenue from External Customer [Line Items]
Revenue	432	432	1,175	1,201
Swine
Revenue from External Customer [Line Items]
Revenue	145	163	441	495
Poultry
Revenue from External Customer [Line Items]
Revenue	111	132	351	399
Fish
Revenue from External Customer [Line Items]
Revenue	25	0	64	0
Other
Revenue from External Customer [Line Items]
Revenue	22	23	60	60
Companion Animal:
Revenue from External Customer [Line Items]
Revenue	490	451	1,479	1,299
Horses
Revenue from External Customer [Line Items]
Revenue	33	35	108	117
Dogs and Cats
Revenue from External Customer [Line Items]
Revenue	457	416	1,371	1,182
Contract Manufacturing
Revenue from External Customer [Line Items]
Revenue	$ 16	$ 13	$ 41	$ 37