| Intangible Assets Activity (Detail) - USD ($) | Aug. 31, 2018 | May 31, 2018 | 
|---|---|---|
| Acquired Finite-Lived Intangible Assets [Line Items] | ||
| Gross carrying amounts | $ 3,500,000 | $ 3,500,000 | 
| Accumulated amortization | (2,056,365) | (1,968,846) | 
| Total amortizable intangible assets, net | 1,443,635 | 1,531,154 | 
| Patents currently not amortized | 35,989 | 35,989 | 
| Carrying value of intangibles, net | $ 1,479,624 | $ 1,567,143 | 
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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 Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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