Derivative Liability - Additional Information (Detail) - USD ($)  | 
12 Months Ended | ||
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May 31, 2018  | 
May 31, 2017  | 
May 31, 2016  | 
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| Derivative [Line Items] | |||
| Change in fair value of derivative liability | $ 1,690,935 | $ 2,164,533 | $ 646,505 | 
| Warrants and Non-cash Interest Expense | |||
| Derivative [Line Items] | |||
| Changes in the fair value of the liability | $ 540,000 | ||
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- Definition 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. No definition available. 
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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of addition (reduction) to the amount at which a liability could be incurred (settled) in a current transaction between willing parties. No definition available. 
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- Details 
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