Contingencies and Commitments - Commitments - Narrative (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Commitments Disclosure [Line Items]
Operating leases, rent expense	$ 1,288,000,000	$ 1,204,000,000	$ 701,000,000
Purchase commitments
Purchase commitments - 2012	10,800,000,000
Purchase commitments - 2013	4,300,000,000
Purchase commitments - 2014	3,300,000,000
Purchase commitments - 2015	3,200,000,000
Purchase commitments - 2016	1,900,000,000
Purchase commitments - After 2016	10,300,000,000
Estimated cost to acquire certain equity ownership interests of less than wholly-owned subsidiaries	$ 4,000,000,000