Annual report pursuant to Section 13 and 15(d)

Activity Related to Notes (Detail)

v3.20.2
Activity Related to Notes (Detail) - USD ($)
3 Months Ended 12 Months Ended
Jan. 31, 2018
Nov. 30, 2019
May 31, 2020
May 31, 2019
May 31, 2018
Sep. 30, 2019
Debt Instrument [Line Items]            
Face amount of Note     $ 0      
Registered direct offering     0 $ (3,586,035)    
Accrued interest converted into principal     153,876 225,245    
Repayment of principal and interest on convertible note     (1,725,000)      
Short-Term Convertible Notes            
Debt Instrument [Line Items]            
Face amount of Note     6,038,500      
Unamortized discount     0      
Registered direct offering     (5,788,500)      
Repayment of principal and interest on convertible note $ (259,000)   (250,000)      
Carrying value of Note     0      
2019 Short Term Convertible Notes            
Debt Instrument [Line Items]            
Face amount of Note     5,460,000 5,460,000 $ 0  
Unamortized discount     0 (1,469,625) 0  
Registered direct offering           $ (5,900,000)
Unamortized issuance costs     0 (404,340) 0  
Accrued interest converted into principal     153,876 0 0  
Repayment of principal and interest on convertible note   $ (700,000) (460,000) 0 0  
Note conversions into common stock     (5,153,876) 0 0  
Carrying value of Note     $ 0 $ 3,586,035 $ 0