Shareholders Equity (Details 2) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011
Treasury Stock [Roll Forward]
Treasury Stock, Shares, Beginning (in shares)	15,508
Treasury Stock, Value, Beginning	$ 124
Purchases (in shares)	97,309	[1]
Purchases	718	[1]	309
Cancellations (in shares)	(62,936)
Cancellations	0
Treasury Stock, Shares, Ending (in shares)	49,881
Treasury Stock, Value, Ending	361
Treasury Stock [Member]
Treasury Stock [Roll Forward]
Purchases	718		309
Cancellations	$ (481)

[1] (1)Includes associated fees.