Reconciliation of Denominator Used in Computation of Basic and Diluted Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								6 Months Ended	12 Months Ended
	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	Nov. 30, 2014	May 31, 2016	May 31, 2015	May 31, 2014
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount										47	5	3
Denominator:
Denominator for basic earnings per share—weighted average common shares outstanding (including shares issuable for vested restricted stock units)										24,414	24,360	24,325
Effect of unvested restricted stock units										15	18	32
Diluted shares used in per share calculation										24,429	24,378	24,357
Net income	$ (885)	$ 1,009	$ 2,190	$ 2,470	$ 3,441	$ 2,425	$ 4,795	$ 4,771	$ 15,432	$ 4,784	$ 15,432	$ 20,408
Earnings per share:
Basic, in dollars per share	$ (0.04)	$ 0.04	$ 0.09	$ 0.10	$ 0.14	$ 0.10	$ 0.20	$ 0.20	$ 0.63	$ 0.20	$ 0.63	$ 0.84
Diluted, in dollars per share	$ (0.04)	$ 0.04	$ 0.09	$ 0.10	$ 0.14	$ 0.10	$ 0.20	$ 0.20	$ 0.63	$ 0.20	$ 0.63	$ 0.84