Quarterly report pursuant to Section 13 or 15(d)

Reconciliation of Liability Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail)

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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