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	$ 49	$ 64
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	97,966,802	95,891,809
Common stock, shares outstanding	93,288,936	92,984,016
Treasury stock, shares	4,677,866	2,907,793