Computation of Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Denominator:
Denominator for basic earnings per share - weighted average common shares outstanding (including shares issuable for vested restricted stock units)	24,440	24,404	24,426	24,380
Effect of unvested restricted stock units	7	4	7	13
Diluted shares used in per share calculation	24,447	24,408	24,433	24,393
Net income	$ 2,190	$ 4,795	$ 4,660	$ 9,566
Earnings per share:
Basic (in dollars per share)	$ 0.09	$ 0.20	$ 0.19	$ 0.39
Diluted (in dollars per share)	$ 0.09	$ 0.20	$ 0.19	$ 0.39
Antidilutive securities excluded from computation of earnings per share (shares)	113	83	113	83

Denominator.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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