Stockholders' Equity (Details) (USD $) Share data in Millions, except Per Share data	3 Months Ended				6 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2010	Mar. 31, 2010	Jun. 30, 2011	Jun. 30, 2010
Dividends paid on common stock					$ 140,000,000	$ 142,000,000
Common stock, cash paid on dividends, per share	$ 0.17	$ 0.16	$ 0.16	$ 0.16
Stock Repurchase Program, 2010 [Member]
Authorized repurchase of common shares under share repurchase program					3,500,000,000
Common shares repurchased					15.2
Repurchases of common stock					1,300,000,000
Repurchase amount of common shares per share					$ 84.52
Total Repurchases [Member]
Common shares repurchased					33.5
Repurchases of common stock					$ 2,500,000,000
Repurchase amount of common shares per share					$ 74.16