Changes in Goodwill and Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Goodwill And Intangible Assets [Line Items]
Goodwill beginning balance	$ 37,297	$ 37,856
Foreign currency	436	(559)
Divestitures	(11,932)
Asset impairments
Acquisitions
Other
Goodwill ending balance	25,801	37,297
Intangible Assets, at cost beginning balance	25,712	26,279
Foreign currency, Intangible Assets, at Cost	262	(567)
Divestitures, Intangible Assets, at cost	(2,669)
Asset impairments, Intangible Assets, at Cost	(52)
Acquisitions, Intangible Assets, at Cost	14
Other	2
Intangible Assets, at cost ending balance	$ 23,269	$ 25,712