EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2016	May 31, 2015
EARNINGS PER SHARE [Abstract]
Net income	$ 16,837	$ 21,195	$ 66,451	$ 66,677
Less: Allocation of income to unvested stockholders	(288)	(257)	(1,041)	(856)
Net earnings available to common stockholders	$ 16,549	$ 20,938	$ 65,410	$ 65,821
Basic weighted average shares outstanding	29,951	29,883	29,918	29,834
Add dilutive effect of stock options (two-class method)	4	5	5	7
Diluted average shares outstanding	29,955	29,888	29,923	29,841
Basic net income per share	$ 0.55	$ 0.70	$ 2.19	$ 2.20
Diluted net income per share	$ 0.55	$ 0.70	$ 2.19	$ 2.20