Consolidated Balance Sheet (Parenthetical) (Unaudited) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.75	$ 0.75
Common stock, shares authorized	6,000,000,000	6,000,000,000
Common stock, shares issued	2,442,676,580	2,442,676,580
Treasury stock, shares	503,698,805	495,978,691