Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 0.5	$ 0.5
Common stock, shares authorized	1,500,000,000	1,500,000,000
Common stock, shares issued	530,315,453	525,817,549
Treasury stock, shares	103,637,016	89,707,087