Organization - Additional Information (Detail)  | 
12 Months Ended | 
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 May. 31, 2015  
Patent 
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| Organization Consolidation And Presentation Of Financial Statements [Line Items] | |
| Number of patent license agreements | 3 | 
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- Definition Number of patent license agreement. No definition available. 
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- Definition Organization Consolidation And Presentation Of Financial Statements [Line Items] No definition available. 
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