Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	May 31, 2012	Aug. 31, 2011
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 10,821	$ 16,095
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	129,060,664	129,060,664
Common stock, shares outstanding	115,974,916	115,533,763
Treasury stock, shares	13,085,748	13,526,901