Summary of Fair Value Warrant Derivative Liability and Related Common Shares (Detail) - USD ($)		Aug. 31, 2018	May 31, 2018	Sep. 15, 2016
Derivative [Line Items]
Derivative liability	[1]	$ 2,071,199	$ 1,323,732
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		$ 2,071,199	$ 1,323,732	$ 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 August 31, 2018 and May 31, 2018.