Quarterly report pursuant to Section 13 or 15(d)

Convertible Instruments and Accrued Interest - Preferred stock (Details)

v3.23.4
Convertible Instruments and Accrued Interest - Preferred stock (Details)
$ / shares in Units, shares in Thousands, $ in Thousands
 6 Months Ended 12 Months Ended
Nov. 30, 2023
USD ($)
$ / shares
shares
May 31, 2023
USD ($)
$ / shares
shares
Class of Stock [Line Items]    
Accumulated deficit | $ $ (862,824) $ (841,690)
Accrued dividends | $ $ 6,049 $ 5,308
Preferred stock, par value | $ / shares $ 0.001 $ 0.001
Series B Convertible Preferred Stock    
Class of Stock [Line Items]    
Shares of preferred stock 19 19
Common stock conversion rate 10 10
Total shares of common stock if converted 190 190
Undeclared dividend | $ $ 17 $ 15
Total shares of common stock if dividends converted 34 30
Preferred Stock, Liquidation Preference Per Share | $ / shares $ 5.00  
Preferred stock, par value | $ / shares $ 0.001 $ 0.001
Series C Convertible Preferred Stock    
Class of Stock [Line Items]    
Shares of preferred stock 6 6
Common stock conversion rate 2,000 2,000
Total shares of common stock if converted 12,670 12,670
Accrued dividends | $ $ 2,818 $ 2,500
Total shares of common stock if dividends converted 5,636 5,000
Preferred stock, par value | $ / shares $ 0.001 $ 0.001
Series D Convertible Preferred Stock    
Class of Stock [Line Items]    
Shares of preferred stock 9 9
Common stock conversion rate 1,250 1,250
Total shares of common stock if converted 10,565 10,565
Accrued dividends | $ $ 3,231 $ 2,808
Total shares of common stock if dividends converted 6,462 5,616
Preferred stock, par value | $ / shares $ 0.001 $ 0.001
Series C and Series D Convertible Preferred Stock    
Class of Stock [Line Items]    
Preferred Stock, Liquidation Preference Per Share | $ / shares $ 1,000