Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accounts receivable, allowance for doubtful accounts	$ 307	$ 273
Other intangible assets, accumulated amortization	250	164
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,200,000,000	1,200,000,000
Common stock, shares issued	810,312,922	807,573,277
Common stock, shares outstanding	743,875,691	765,186,316
Treasury stock, shares	66,437,231	42,386,961
Variable Interest Entity [Line Items]
Non-recourse debt - current, balance at variable interest entities	2,324	2,123
Non-recourse debt - noncurrent, balance at variable interest entities	13,049	13,412
Consolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Non-recourse debt - current, balance at variable interest entities	294	259
Non-recourse debt - noncurrent, balance at variable interest entities	$ 1,173	$ 1,156