Supplemental Equity and Comprehensive Income Information (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Supplemental Equity and Comprehensive Income Information
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	3,000,000,000
Common stock, shares issued (in shares)	944,033,056
Treasury stock (in shares)	249,063,015	232,055,448	233,433,937	250,489,769
Preferred stock, par value
Preferred stock, shares authorized	10,000,000
Preferred stock, shares issued	0