CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	May. 31, 2015	Aug. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 7,498	$ 5,908
Common stock, par value (in USD per share)	$ 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	115,601,037	117,829,262
Treasury stock, shares	13,459,627	11,231,402