Quarterly report pursuant to Section 13 or 15(d)

Acquisition of patents - Additional Information (Detail)

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Acquisition of patents - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Oct. 16, 2012
Feb. 28, 2018
Feb. 28, 2017
Feb. 28, 2018
Feb. 28, 2017
Acquired Finite-Lived Intangible Assets [Line Items]          
Asset purchase, cash paid $ 3,500,000        
Intangible asset acquired gross   $ 3,500,000   $ 3,500,000  
Estimated aggregate future amortization expense in next twelve months   350,000   350,000  
Estimated aggregate future amortization expense in year two   350,000   350,000  
Estimated aggregate future amortization expense in year three   350,000   350,000  
Estimated aggregate future amortization expense in year four   350,000   350,000  
Estimated aggregate future amortization expense in year five   350,000   350,000  
Patents          
Acquired Finite-Lived Intangible Assets [Line Items]          
Asset purchase, cash paid $ 3,500,000        
Estimated useful life of acquired asset 10 years        
Amortization expense related to acquired patents   $ 87,500 $ 87,500 $ 262,500 $ 262,500