Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Earnings Per Share [Abstract]
Net income		$ 10,819	$ 7,662	$ 23,277	$ 17,747
Weighted average common shares outstanding – basic		48,977	53,171	49,599	53,226
Effect of dilutive employee stock options and unvested restricted stock units		1,011	1,489	1,057	1,518
Weighted average common shares outstanding - diluted		49,988	54,660	50,656	54,744
Net income per common share - basic		$ 0.22	$ 0.14	$ 0.47	$ 0.33
Net income per common share - diluted		$ 0.22	$ 0.14	$ 0.46	$ 0.32
Anti-dilutive securities excluded	[1]	552	173	482	313

[1] Anti-dilutive securities consist of stock options and unvested restricted stock units that were not included in the computation of diluted earnings per share because either the exercise price of the options was greater than the average market price of the common stock or the total assumed proceeds under the treasury stock method resulted in negative incremental shares and thus the inclusion would have been anti-dilutive.