Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 104	$ 134
Other intangible assets, accumulated amortization	156	153
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)	814,456,569	813,316,510
Common stock, shares outstanding (in shares)	715,960,427	722,508,342
Treasury stock, shares (in shares)	98,496,142	90,808,168
Variable Interest Entity [Line Items]
Non-recourse debt - current balance at variable interest entities	2,347	2,062
Consolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Non-recourse debt - current balance at variable interest entities	242	267
Non-recourse debt - current balance at variable interest entities	$ 1,036	$ 979