Annual report [Section 13 and 15(d), not S-K Item 405]

Convertible Instruments and Accrued Interest - Additional Information (Details)

v3.26.1
Convertible Instruments and Accrued Interest - Additional Information (Details)
1 Months Ended 12 Months Ended
Apr. 23, 2021
USD ($)
$ / shares
shares
Apr. 02, 2021
USD ($)
Apr. 30, 2026
USD ($)
Apr. 30, 2025
USD ($)
Apr. 30, 2023
May 31, 2026
USD ($)
Agreement
$ / shares
shares
May 31, 2025
USD ($)
$ / shares
Debt Instrument              
Accumulated deficit           $ (930,485,000) $ (887,786,000)
Undeclared dividend, shares | shares           10  
Preferred stock, par value | $ / shares           $ 0.001 $ 0.001
Gain on restructuring of payables           $ 0 $ 407,000
Number of days average of share prices     5        
Series B Convertible Preferred Stock              
Debt Instrument              
Preferred stock dividend, value per share | $ / shares           $ 0.25  
Preferred stock conversion price, per share | $ / shares           0.5  
Preferred stock, liquidation preference per share ($ per share) | $ / shares           5  
Preferred stock, par value | $ / shares           0.001 $ 0.001
Series C Convertible Preferred Stock              
Debt Instrument              
Preferred stock conversion price, per share | $ / shares           0.5  
Preferred stock, liquidation preference per share ($ per share) | $ / shares           $ 1,000  
Preferred stock dividend rate, as a percent           10.00%  
Fractional shares | shares           0  
Preferred stock, par value | $ / shares           $ 0.001 0.001
Series D Convertible Preferred Stock              
Debt Instrument              
Preferred stock conversion price, per share | $ / shares           0.8  
Preferred stock, liquidation preference per share ($ per share) | $ / shares           $ 1,000  
Preferred stock dividend rate, as a percent           10.00%  
Fractional shares | shares           0  
Preferred stock, par value | $ / shares           $ 0.001 $ 0.001
Long-term Convertible Note - April 2, 2021 Note              
Debt Instrument              
Convertible note, aggregate principal   $ 28,500,000          
Consideration received   25,000,000          
Unamortized discount   3,400,000          
Debt issuance costs   $ 100,000          
Convertible notes, interest rate   10.00% 5.00%        
Percentage increase in amount payable on default   15.00%          
Percentage increase in amount payable, second scenario   10.00%          
Percentage increase in amount payable, third default scenario   5.00%          
Debt proceeds requiring investor consent   $ 50,000,000          
Additional debt, increase in interest rate   5.00%          
Conversion price per share | $ / shares $ 10            
Number of days of notice to be given for conversion of notes into common stock 5 days            
Shares reserved | shares 6,000,000            
Debt instrument prepayment percentage premium 15.00%            
Number of days of notice to be given for prepayment 15 days            
Long-term Convertible Note - April 2, 2021 Note | Maximum              
Debt Instrument              
Convertible notes, interest rate     22.00%        
Long-term Convertible Note - April 23, 2021 Note              
Debt Instrument              
Convertible note, aggregate principal $ 28,500,000         $ 9,500,000  
Consideration received 25,000,000            
Unamortized discount 3,400,000            
Debt issuance costs $ 100,000            
Convertible notes, interest rate 5.00%            
Percentage increase in amount payable on default 15.00%            
Percentage increase in amount payable, second scenario 10.00%            
Percentage increase in amount payable, third default scenario 5.00%            
Debt proceeds requiring investor consent $ 75,000,000            
Additional debt, increase in interest rate 5.00%            
Conversion price per share | $ / shares $ 10            
Number of days of notice to be given for conversion of notes into common stock 5 days            
Shares reserved | shares 6,000,000            
Number of exchange agreements | Agreement           12  
Conversion of Series C preferred stock to common stock (in shares) | shares           32,600,000  
Debt instrument outstanding, balance           $ 29,600,000  
Long-term Convertible Note - April 23, 2021 Note | Maximum              
Debt Instrument              
Convertible notes, interest rate 10.00%     22.00%      
Long-term Convertible Note - April 2, 2021 Note and April 23, 2021 Note Extensions              
Debt Instrument              
Debt instrument, extended term     3 years 1 year 2 years    
Extension fees percentage     5.00% 6.00% 2.50%    
Debt instrument increase in debt $ 900,000 $ 300,000          
Specified monthly redemption amount     $ 1,000,000 $ 750,000      
Number of days average of share prices       5