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, 2018	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Numerator:
Net income	$ 18,592	$ 21,576	$ 19,607	$ 11,430	$ 20,831	$ 18,751	$ 10,963	$ 13,118	$ 71,205	$ 63,663	$ 64,067
Denominator:
Weighted average common shares outstanding - basic (in shares)									37,618	43,306	48,703
Effect of dilutive employee stock options and unvested RSUs (in shares)									468	737	966
Weighted average common shares outstanding - diluted (in shares)									38,086	44,043	49,669
Net income per common share - basic (usd per share)	$ 0.52	$ 0.58	$ 0.51	$ 0.29	$ 0.50	$ 0.44	$ 0.25	$ 0.29	$ 1.89	$ 1.47	$ 1.32
Net income per common share - diluted (usd per share)	$ 0.51	$ 0.58	$ 0.51	$ 0.29	$ 0.50	$ 0.44	$ 0.25	$ 0.28	$ 1.87	$ 1.45	$ 1.29
Anti-dilutive securities excluded (in shares)									1,157	1,154	615