Summary of Fair Value Warrant Derivative Liability and Related Common Shares (Detail) - USD ($)		May 31, 2018	May 31, 2017	Sep. 15, 2016
Derivative [Line Items]
Derivative Liability	[1]	$ 1,323,732	$ 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	7,333,334
Derivative Liability		$ 1,323,732	$ 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 May 31, 2018 and May 31, 2017.