Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Aug. 31, 2012	Aug. 31, 2011
Current Assets:
Allowance for doubtful accounts	$ 1.4	$ 1.8
Stockholders' Equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Preferred stock, issued (in shares)
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, issued (in shares)	51,508,358	50,956,137
Common stock, outstanding (in shares)	41,789,103	41,488,882
Treasury stock (in shares)	9,719,255	9,467,255