CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	May 31, 2017	Aug. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 4,986	$ 6,427
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	115,788,992	114,635,596
Treasury stock, shares	13,271,672	14,425,068