CONDENSED 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	$ 32	$ 33
Accumulated depreciation and amortization	$ 16,998	$ 16,723
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,500,000,000	1,500,000,000
Common stock, shares issued	630,282,461	630,282,461
Treasury stock, shares	164,396,943	165,961,646