Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Statement of Financial Position [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	541,245,735	539,664,386
Treasury stock, shares	160,221,798	144,459,210