Consolidated Balance Sheets (Parenthetical) (USD $)	Aug. 31, 2012	Aug. 31, 2011
Consolidated Balance Sheets [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	245,000,000	245,000,000
Common stock, shares issued	118,309,094	118,309,094
Treasury stock, shares	60,324,576	56,315,651