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 ($)
 3 Months Ended 9 Months Ended 12 Months Ended
Feb. 29, 2020
Feb. 29, 2020
May 31, 2019
May 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Beginning Balance   $ 2,407,269 $ 1,323,732  
Exercises $ 5,427,687      
Fair value adjustments       $ (3,855,468)
Ending Balance $ 2,108,398 2,108,398 2,407,269 1,323,732
Convertible notes [Member]        
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Fair value adjustments   (2,005,137) (921,600)  
Warrant [Member]        
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Exercises   (2,404,097)    
Fair value adjustments   $ 4,110,363 (744,869)  
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
Inception date value of redemption provision - warrants        
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Warrants issued     $ 2,750,006