Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Balance Sheet Parentheticals [Abstract]
Receivables, allowances	$ 82	$ 81
Class A Common Stock
Class Of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	375,000,000	375,000,000
Common stock, shares, issued	42,000,000	43,000,000
Class B Common Stock
Class Of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	5,000,000,000	5,000,000,000
Common stock, shares, issued	793,000,000	785,000,000
Treasury stock, at cost, Class B shares	222,000,000	198,000,000