Quarterly report pursuant to Section 13 or 15(d)

Convertible Instruments and Accrued Interest - Preferred stock (Details)

v3.22.4
Convertible Instruments and Accrued Interest - Preferred stock (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 6 Months Ended 12 Months Ended
Nov. 30, 2022
May 31, 2022
Class of Stock [Line Items]    
Accrued dividends $ 4,571 $ 3,977
Series B Convertible Preferred Stock    
Class of Stock [Line Items]    
Shares of preferred stock 19 19
Total shares of common stock if converted 190 190
Undeclared dividend $ 12 $ 10
Total shares of common stock if dividends converted 25 20
Preferred stock dividend, value per share $ 0.25  
Preferred stock, stated value per share 5.00  
Preferred stock conversion price, per share $ 0.50  
Undeclared dividend, shares 10  
Series C Convertible Preferred Stock    
Class of Stock [Line Items]    
Shares of preferred stock 6 7
Total shares of common stock if converted 12,670 13,806
Accrued dividends $ 2,184 $ 2,014
Total shares of common stock if dividends converted 4,368 4,028
Preferred stock dividend, value per share $ 0.50  
Series D Convertible Preferred Stock    
Class of Stock [Line Items]    
Shares of preferred stock 9 9
Total shares of common stock if converted 10,565 10,565
Accrued dividends $ 2,387 $ 1,963
Total shares of common stock if dividends converted 4,774 3,926
Preferred stock dividend, value per share $ 0.80  
Series C and Series D Convertible Preferred Stock    
Class of Stock [Line Items]    
Preferred stock dividend rate, as a percent 10.00%  
Preferred stock, stated value per share $ 1,000