Quarterly report pursuant to Section 13 or 15(d)

Convertible Instruments - Preferred stock (Detail)

v3.21.1
Convertible Instruments - Preferred stock (Detail) - USD ($)
 9 Months Ended 12 Months Ended
Feb. 28, 2021
Jul. 30, 2020
Feb. 28, 2021
May 31, 2020
Class of Stock [Line Items]        
Preferred stock, shares authorized 5,000,000   5,000,000 5,000,000
Preferred stock, par value $ 0.001   $ 0.001 $ 0.001
Accrued dividends $ 2,227,000   $ 2,227,000 $ 981,000
Series D Convertible Preferred Stock        
Class of Stock [Line Items]        
Preferred stock, shares authorized 11,757   11,757 12,000
Preferred stock, par value $ 0.001   $ 0.001 $ 0.001
Preferred stock, shares outstanding 8,452   8,452 9,000
Preferred stock dividend rate, as a percent 10.00%   10.00%  
Preferred stock dividend, value per share     $ 0.50  
Preferred stock, stated value per share $ 1,000.00   1,000.00  
Preferred stock conversion price, per share $ 0.80   $ 0.80  
Accrued dividends $ 900,000   $ 900,000 $ 300,000
Accrued dividend, in shares of common stock 1,800,000   1,800,000 500,000
Series C Convertible Preferred Stock        
Class of Stock [Line Items]        
Preferred stock, shares authorized 8,203   8,203 8,000
Preferred stock, par value $ 0.001   $ 0.001 $ 0.001
Preferred stock, shares outstanding 8,203   8,203 8,000
Preferred stock dividend rate, as a percent 10.00%   10.00%  
Preferred stock, stated value per share $ 1,000.00   $ 1,000.00  
Preferred stock conversion price, per share $ 0.50   $ 0.50  
Accrued dividends $ 1,300,000   $ 1,300,000 $ 700,000
Accrued dividend, in shares of common stock 2,600,000   2,600,000 1,400,000
Series B Convertible Preferred Stock        
Class of Stock [Line Items]        
Preferred stock, shares authorized 400,000   400,000 400,000
Preferred stock, par value $ 0.001   $ 0.001 $ 0.001
Preferred stock, shares outstanding 79,100   79,100 92,000
Preferred stock dividend, value per share     $ 0.25  
Preferred stock, stated value per share $ 5.00   $ 5.00  
Number of shares issued upon conversion 10   10  
Preferred stock conversion price, per share $ 0.50   $ 0.50  
Preferred stock cash dividend declared   $ 200,000    
Undeclared dividend     $ 12,319 $ 200,000
Undeclared dividend, shares     24,636 500,000