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Goodwill and Other Intangibles - Goodwill Activity by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 18,284	$ 18,162
Acquisitions	41	177
Impairments	(144)	(38)
Other	72	(17)
Goodwill, Ending Balance	18,253	18,284
Accumulated goodwill impairment losses	369	225
Pharmaceutical
Goodwill [Roll Forward]
Goodwill, Beginning Balance	16,066	16,075
Acquisitions	0	0
Impairments	0	0
Other	96	(9)
Goodwill, Ending Balance	16,162	16,066
Animal Health
Goodwill [Roll Forward]
Goodwill, Beginning Balance	1,877	1,708
Acquisitions	17	177
Impairments	0	0
Other	(24)	(8)
Goodwill, Ending Balance	1,870	1,877
All Other
Goodwill [Roll Forward]
Goodwill, Beginning Balance	341	379
Acquisitions	24	0
Impairments	(144)	(38)
Other	0	0
Goodwill, Ending Balance	$ 221	$ 341

X

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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