Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data	May 31, 2011	Aug. 31, 2010
Current Assets:
Allowance for doubtful accounts	$ 1.7	$ 2.0
Stockholders' Equity:
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, issued	50,905,733	50,441,634
Common stock, outstanding	42,650,978	42,116,473
Treasury stock	8,254,755	8,325,161