Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 134	$ 195
Other intangible assets, accumulated amortization	153	222
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,200,000,000	1,200,000,000
Common stock, shares issued (in shares)	813,316,510	810,679,839
Common stock, shares outstanding (in shares)	722,508,342	744,263,855
Treasury stock, shares (in shares)	90,808,168	66,415,984
Variable Interest Entity [Line Items]
Non-recourse debt - current balance at variable interest entities	2,062	2,494
Non-recourse debt - noncurrent, balance at variable interest entities	13,318	12,265
Consolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Non-recourse debt - current balance at variable interest entities	267	275
Non-recourse debt - noncurrent, balance at variable interest entities	$ 979	$ 858