Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 9	$ 9
Preferred stock:
Shares issued	0	0
Shares outstanding	0	0
Par value	$ 0.01000000
Shares authorized	30,000,000
Common stock:
Shares issued	363,000,000	362,000,000
Par value	$ 0.01000000
Shares authorized	1,000,000,000
Treasury stock	(78,000,000)	(65,000,000)