Shareholders' Equity (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended			3 Months Ended	9 Months Ended
	Aug. 31, 2011	May 31, 2011 installment	Dec. 31, 2008 subsidiary	Sep. 30, 2011 installment	Sep. 30, 2012	Sep. 30, 2011 installment	Dec. 31, 2011
Distribution of qualifying additional paid-in capital
Cash distribution approved in the form of additional paid-in capital (in dollars per share)		$ 3.16
Number of quarterly installments (in installments)		4
Amount of installment (in dollars per share)		$ 0.79
Number of installments paid (in installments)				2		2
Installment of dividend paid	$ 508	$ 508		$ 254	$ 278	$ 508
Shares held by subsidiary
Number of issued shares to a subsidiary to satisfy obligations in connection with awards granted under incentive plans or other rights to acquire shares of stocks			16
Number of subsidiaries to whom shares were issued			1
Number of shares held by subsidiary					12		12