Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Equity:
Preferred stock, par value	$ 0.10	$ 0.10
Preferred stock, authorized	5,000,000	5,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.20	$ 0.20
Common stock, authorized	500,000,000	500,000,000
Common stock, shares issued	136,017,732	137,520,019
Common stock, shares outstanding	136,018,000	137,520,000
Treasury stock, at cost	99,100,186	97,597,899