Shareholders Equity (Details 2) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Treasury Stock [Roll Forward]
Treasury Stock, Shares, Beginning (shares)	14,924
Purchases (in shares)	1,360	[1]
Cancellations (in shares)	(16,284)
Treasury Stock, Shares, Ending (shares)	0
Treasury Stock, Value, Beginning	$ 104
Purchases	10	[1]	50
Cancellation of treasury stock	(114)		0
Treasury Stock, Value, Ending	$ 0

[1] (1)Includes associated fees.