Calculation of Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Aug. 31, 2019	Aug. 31, 2018
Earnings Per Share [Line Items]
Numerator for basic and diluted net income per share - Net income	$ 14,652	$ 15,237
Denominator for basic net income per share - Weighted average shares	52,292	51,806
Effect of dilutive stock options	392	974
Denominator for diluted net income per share	52,684	52,780
Net income per share:
Basic	$ 0.28	$ 0.29
Diluted	$ 0.28	$ 0.29