Segment and Other Revenue Information (Revenue by Animal Species) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2013	Sep. 29, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenue from External Customer [Line Items]
Revenue	$ 1,320	$ 1,210	$ 1,158	$ 1,097	$ 1,254	$ 1,103	$ 1,114	$ 1,090	$ 4,785	[1]	$ 4,561	[1]	$ 4,336	[1]
Livestock [Member]
Revenue from External Customer [Line Items]
Revenue									3,103		2,916		2,795
Cattle
Revenue from External Customer [Line Items]
Revenue									1,747		1,628		1,603
Swine
Revenue from External Customer [Line Items]
Revenue									695		652		592
Poultry
Revenue from External Customer [Line Items]
Revenue									568		551		506
Other (Fish and Sheep)
Revenue from External Customer [Line Items]
Revenue									93		85		94
Companion Animal [Member]
Revenue from External Customer [Line Items]
Revenue									1,632		1,592		1,513
Horses
Revenue from External Customer [Line Items]
Revenue									182		179		185
Dogs and Cats
Revenue from External Customer [Line Items]
Revenue									1,450		1,413		1,328
Contract Manufacturing [Member]
Revenue from External Customer [Line Items]
Revenue									$ 50		$ 53		$ 28

[1] Revenue denominated in euros were $710 million in 2014, $693 million in 2013, and $639 million in 2012.