Share Repurchase Program (Details) (USD $) Share data in Millions, except Per Share data	1 Months Ended	9 Months Ended	12 Months Ended	1 Months Ended	9 Months Ended
	Oct. 31, 2010 October 2011 Program [Member]	Sep. 30, 2011 October 2011 Program [Member]	Sep. 30, 2011 October 2011 Program [Member]	Sep. 30, 2011 September 2011 Program [Member]	Sep. 30, 2011 September 2011 Program [Member] Minimum [Member]
Share Repurchase Program [Line Items]
Shares authorized for repurchase, maximum shares	65
Shares authorized for repurchase, maximum value	$ 1,000,000,000			$ 1,000,000,000
Shares repurchased, value		600,000,000	800,000,000
Shares repurchased, shares		22.1	30.1
Shares repurchased, average price per share		$ 27.13	$ 26.55
Stock repurchase program, authorized amount		200,000,000
Stock repurchase program, planned repurchase value					$ 500,000,000