Quarterly report pursuant to Section 13 or 15(d)

Summary of Fair Value Warrant Derivative Liability and Related Common Shares (Detail)

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Summary of Fair Value Warrant Derivative Liability and Related Common Shares (Detail) - USD ($)
Feb. 28, 2018
May 31, 2017
Sep. 15, 2016
Derivative [Line Items]      
Derivative liability [1] $ 3,288,799 $ 3,014,667  
Registered Direct Equity Offering | Investor Warrants Issued with Registered Direct Equity Offering      
Derivative [Line Items]      
Shares indexed 7,733,334 7,733,334 7,733,334
Derivative liability $ 3,288,799 $ 3,014,667 $ 5,179,200
[1] The Company did not have any assets or liabilities measured at fair value using Level 1 or 2 of the fair value hierarchy as of February 28, 2018 and May 31, 2017.