Annual report pursuant to Section 13 and 15(d)

Convertible Instruments - 2019 Short-term Convertible Notes (Detail)

v3.21.2
Convertible Instruments - 2019 Short-term Convertible Notes (Detail)
 2 Months Ended 3 Months Ended 12 Months Ended
Nov. 14, 2019
USD ($)
item
Nov. 30, 2019
USD ($)
item
$ / shares
shares
May 31, 2021
USD ($)
$ / shares
shares
May 31, 2020
USD ($)
$ / shares
shares
May 31, 2019
USD ($)
$ / shares
shares
Mar. 13, 2020
$ / shares
shares
Aug. 31, 2019
$ / shares
shares
Short-term Debt [Line Items]              
Common stock warrants to purchase shares | shares           300,000 2,600,000
Exercise price of warrants, per share | $ / shares           $ 1.00 $ 0.50
Term of warrants           5 years 5 years
Debt discount costs related to debt offering         $ 3,059,000    
Amortization of debt discount     $ 3,591,000 $ 1,645,000 1,707,000    
Debt issuance costs     65,000 404,000 459,000    
Inducement interest expense, debt     $ 11,366,000 7,904,000 196,000    
Shares issued on debt conversion | shares     19,900,000        
Minimum              
Short-term Debt [Line Items]              
Exercise price of warrants, per share | $ / shares     $ 0.30        
Maximum              
Short-term Debt [Line Items]              
Exercise price of warrants, per share | $ / shares     $ 1.35        
Two Thousand And Nineteen Short Term Convertible Notes [Member]              
Short-term Debt [Line Items]              
Convertible note, aggregate principal       $ 5,460,000 $ 5,460,000    
Debt instrument term         9 months    
Conversion price per share | $ / shares   $ 0.50   $ 0.50 $ 0.50    
Convertible notes, interest rate         10.00%    
Common stock warrants to purchase shares | shares         5,460,000    
Exercise price of warrants, per share | $ / shares         $ 0.30    
Term of warrants         5 years    
Amortization of debt discount         $ 1,700,000    
Debt issuance costs         500,000    
Carrying value, current $ 5,900,000     $ 5,200,000 3,586,000    
Amount extended for three months 1,100,000            
Amount extended for six months $ 4,100,000            
Number of noteholders converting to equity | item 1            
Repayment of note   $ 700,000   460,000      
Principal amount of debt converted $ 200,000     $ 5,154,000      
Inducement interest expense, debt   $ 300,000          
Shares issued on debt conversion | shares       10,400,000      
Interest expense       $ 400,000 200,000    
Carrying value of Note       $ 0      
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants              
Short-term Debt [Line Items]              
Common stock warrants to purchase shares | shares   4.75          
Exercise price of warrants, per share | $ / shares   $ 0.30          
Term of warrants   5 years          
Debt discount costs related to debt offering         3,100,000    
Debt issuance costs         $ 800,000    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants | Expected Dividend Yield              
Short-term Debt [Line Items]              
Weighted average assumptions         0    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants | Stock Price Volatility | Minimum              
Short-term Debt [Line Items]              
Weighted average assumptions         0.558    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants | Stock Price Volatility | Maximum              
Short-term Debt [Line Items]              
Weighted average assumptions         0.5588    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants | Expected Term (In Years)              
Short-term Debt [Line Items]              
Weighted average assumptions         5    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants | Risk Free Interest Rate | Minimum              
Short-term Debt [Line Items]              
Weighted average assumptions         0.0248    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants | Risk Free Interest Rate | Maximum              
Short-term Debt [Line Items]              
Weighted average assumptions         0.0256    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants | Grant Date Fair Value | Minimum              
Short-term Debt [Line Items]              
Weighted average assumptions         0.0030    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Detachable Common Stock Warrants | Grant Date Fair Value | Maximum              
Short-term Debt [Line Items]              
Weighted average assumptions         0.38    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Placement Agent Warrants              
Short-term Debt [Line Items]              
Common stock warrants to purchase shares | shares         970,000    
Exercise price of warrants, per share | $ / shares         $ 0.50    
Term of warrants         5 years    
Cash fee         $ 600,000    
Two Thousand And Nineteen Short Term Convertible Notes [Member] | Warrants issued to one investor              
Short-term Debt [Line Items]              
Common stock warrants to purchase shares | shares   200,000          
Exercise price of warrants, per share | $ / shares   $ 0.45          
Term of warrants   5 years          
Number of noteholders converting to equity | item   1