Goodwill and Other Intangibles - Goodwill Activity by Segment (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 12,155	$ 12,378
Additions		144
Other	(21)	(367)
Goodwill, Ending Balance	12,134	12,155
Pharmaceutical Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	10,107	10,345
Additions		144
Other	(21)	(382)
Goodwill, Ending Balance	10,086	10,107
Other segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	2,048	2,033
Additions
Other		15
Goodwill, Ending Balance	$ 2,048	$ 2,048