Quarterly report pursuant to Section 13 or 15(d)

Convertible Instruments and Accrued Interest - Preferred stock (Detail)

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Convertible Instruments and Accrued Interest - Preferred stock (Detail) - USD ($)
 6 Months Ended 12 Months Ended
Nov. 30, 2021
May 31, 2021
Class of Stock [Line Items]    
Preferred stock, shares authorized 5,000,000 5,000,000
Preferred stock, par value $ 0.001 $ 0.001
Accrued dividends $ 3,481,000 $ 2,647,000
Common stock, shares authorized 1,000,000,000 1,000,000,000
Series D Convertible Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, shares authorized 11,737 12,000
Preferred stock, par value $ 0.001 $ 0.001
Preferred stock, shares issued 9,000 9,000
Preferred stock, share outstanding 8,452  
Preferred stock dividend rate, as a percent 10.00%  
Preferred stock dividend, value per share $ 0.50  
Preferred stock, stated value per share 1,000  
Preferred stock conversion price, per share $ 0.80  
Accrued dividends $ 1,500,000 $ 1,100,000
Accrued dividend, in shares of common stock 3,000,000.0 2,200,000
Series C Convertible Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, shares authorized 8,203 8,000
Preferred stock, par value $ 0.001 $ 0.001
Preferred stock, shares issued 8,000 8,000
Preferred stock dividend rate, as a percent 10.00%  
Preferred stock dividend, value per share $ 0.50  
Preferred stock, stated value per share 1,000  
Preferred stock conversion price, per share $ 0.50  
Accrued dividends $ 1,900,000 $ 1,500,000
Accrued dividend, in shares of common stock 3,900,000 3,000,000.0
Series B Convertible Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, shares authorized 400,000 400,000
Preferred stock, par value $ 0.001 $ 0.001
Preferred stock, shares issued 19,000 79,000
Preferred stock dividend, value per share $ 0.25  
Preferred stock, stated value per share 5.00  
Preferred stock conversion price, per share $ 0.50  
Number of shares issued upon conversion 10  
Undeclared dividend $ 7,316 $ 17,800
Undeclared dividend, shares 14,631 35,500