EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2017	Feb. 29, 2016	Feb. 28, 2017	Feb. 29, 2016
EARNINGS PER SHARE [Abstract]
Net income	$ 27,219	$ 25,942	$ 52,088	$ 49,614
Less: Allocation of income to unvested stockholders	(345)	(371)	(758)	(742)
Net earnings available to common stockholders	$ 26,874	$ 25,571	$ 51,330	$ 48,872
Basic weighted average shares outstanding	30,004	29,914	29,993	29,902
Add dilutive effect of stock options (two-class method)	4	5	4	5
Diluted average shares outstanding	30,008	29,919	29,997	29,907
Basic net income per share	$ 0.90	$ 0.85	$ 1.72	$ 1.63
Diluted net income per share	$ 0.90	$ 0.85	$ 1.72	$ 1.63