CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Accounts receivable, allowances (in dollars)	$ 102	$ 79
Class A common stock
Common stock and additional paid-in capital, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock and additional paid-in capital, shares authorized	3,947,000,000	3,947,000,000
Common stock and additional paid-in capital, shares issued	636,156,332	691,306,695
Common stock and additional paid-in capital, shares outstanding	636,156,332	691,306,695