Reconciliation of Liability Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Feb. 28, 2018	May 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value adjustments	$ 274,132	$ (2,164,533)
Ending Balance	$ 3,288,799	3,014,667
Investor Warrants Issued with Registered Direct Equity Offering
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Warrants issued		4,360,000
Placement Agent Warrants Issued with Registered Direct Equity Offering
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Warrants issued		$ 819,200