Summary of Fair Value Warrant Derivative Liability and Related Common Shares (Detail) - USD ($)	Aug. 31, 2017		May 31, 2017	Sep. 15, 2016
Derivative [Line Items]
Derivative liability	$ 3,377,333	[1]	$ 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	$ 3,377,333		$ 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 August 31, 2017, and May 31, 2017.