Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended																12 Months Ended
		Aug. 31, 2015		May. 31, 2015		Feb. 28, 2015		Nov. 30, 2014		Aug. 31, 2014		May. 31, 2014		Feb. 28, 2014		Nov. 30, 2013		Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2013
Earnings Per Share [Abstract]
Net income		$ 26,296	[1]	$ 20,442	[1]	$ 7,662	[1]	$ 10,085	[1]	$ 18,825	[1]	$ 16,776	[1]	$ 4,107	[1]	$ 8,208	[1]	$ 64,485	$ 47,916	$ 36,701
Weighted average common shares outstanding - basic																		52,572	55,164	56,384
Effect of dilutive employee stock options and unvested restricted stock units																		1,381	1,455	807
Weighted average common shares - diluted																		53,953	56,619	57,191
Net income per common share - basic		$ 0.51	[2]	$ 0.39	[2]	$ 0.14	[2]	$ 0.19	[2]	$ 0.35	[2]	$ 0.31	[2]	$ 0.07	[2]	$ 0.15	[2]	$ 1.23	$ 0.87	$ 0.65
Net income per common share - diluted		$ 0.50	[2]	$ 0.38	[2]	$ 0.14	[2]	$ 0.18	[2]	$ 0.34	[2]	$ 0.30	[2]	$ 0.07	[2]	$ 0.14	[2]	$ 1.20	$ 0.85	$ 0.64
Anti-dilutive securities excluded	[3]																	342	988	3,278

[1] Includes a tax benefit of $0.7 million from the retroactive reinstatement of the Work Opportunity Tax Credit and resolution of income tax matters in the second quarter of fiscal year 2015; a federal tax benefit of $1.7 million from the recognition of a prior-year statutory tax deduction and a tax expense of $0.6 million from the retroactive effect of federal tax law change during the third quarter of fiscal year 2015; and a federal tax benefit of $1.5 million from the recognition of a prior-year statutory tax deduction and $1.7 million from a change in deferred tax valuation allowance during the fourth quarter of fiscal year 2015. Also includes a $0.5 million tax benefit resulting from the IRS's acceptance of a federal tax method change during the first quarter of fiscal year 2014.

[2] The sum of per share data may not agree to annual amounts due to rounding.

[3] 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.