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, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015
Numerator:
Net income	$ 20,831	$ 18,751	$ 10,963	$ 13,118	$ 25,437	$ 15,353	$ 10,819	$ 12,458	$ 63,663	$ 64,067	$ 64,485
Denominator:
Weighted average common shares outstanding - basic (in shares)									43,306	48,703	52,572
Effect of dilutive employee stock options and unvested RSUs (in shares)									737	966	1,381
Weighted average common shares outstanding - diluted (in shares)									44,043	49,669	53,953
Net income per common share - basic (usd per share)	$ 0.50	$ 0.44	$ 0.25	$ 0.29	$ 0.54	$ 0.32	$ 0.22	$ 0.25	$ 1.47	$ 1.32	$ 1.23
Net income per common share - diluted (usd per share)	$ 0.50	$ 0.44	$ 0.25	$ 0.28	$ 0.53	$ 0.31	$ 0.22	$ 0.24	$ 1.45	$ 1.29	$ 1.20
Anti-dilutive securities excluded (in shares)									1,154	615	342