Equity Compensation Plans - Additional Information (Detail) - USD ($)	3 Months Ended
Aug. 31, 2019	Aug. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value per share of stock options granted	$ 14.91
Compensation expense related to share based awards	$ 1,543,000	$ 1,431,000
Options granted	0
Employee Stock Purchase Plan \| 2011 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual maximum limit percentage of compensation to purchase shares	5.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period	3 years
Stock option contractual terms	5 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period	5 years
Stock option contractual terms	10 years

Share based compensation arrangement by share based payment award, options, contractual term one.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Discount rate from fair value on purchase date that participants pay for shares.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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Gross number of share options (or share units) granted during the period.

+ References

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

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- Definition

Amount of cost expensed and capitalized for award under share-based payment arrangement.

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