CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Allowance for uncollectible accounts	$ 7	$ 5
Common stock, par value	$ 0.1	$ 0.1
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	525,600,000	522,500,000
Treasury stock, shares	19,200,000	18,800,000