Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 0.5	$ 0.5
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	177,880,647	175,985,437
Treasury stock, shares	1,177,959	776,355