Quarterly report pursuant to Section 13 or 15(d)

Private Securities Offerings - Additional Information (Detail)

v3.20.4
Private Securities Offerings - Additional Information (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 6 Months Ended
Nov. 30, 2020
Nov. 17, 2020
Oct. 26, 2020
Oct. 14, 2020
Nov. 30, 2020
Aug. 31, 2020
Nov. 30, 2020
Nov. 30, 2019
May 31, 2020
Equity and Equity Units Offering Disclosure [Line Items]                  
Exercise price of warrants, per share               $ 0.45  
Common stock, par value $ 0.001       $ 0.001   $ 0.001   $ 0.001
Proceeds From Exercise Of Warrants             $ 15,209 $ 0  
March 2020 Long Term Convertible Notes [Member]                  
Equity and Equity Units Offering Disclosure [Line Items]                  
Common stock, par value 0.001       0.001   $ 0.001    
March 2020 Long Term Convertible Notes [Member] | Partitioned Notes [Member]                  
Equity and Equity Units Offering Disclosure [Line Items]                  
Common stock, par value 0.001       $ 0.001   0.001    
Number of shares to be sold         4,300        
Private Warrant Exchange [Member]                  
Equity and Equity Units Offering Disclosure [Line Items]                  
Exercise price of warrants, per share 0.75       $ 0.75   0.75    
Common stock, par value     $ 0.001 $ 0.001          
Proceeds From Exercise Of Warrants     $ 1,600 $ 2,700          
Share Price $ 0.60       0.60   $ 0.60    
Noncash inducement interest expense             $ 200    
Inducement Interest Expense $ 300   $ 1,400 $ 2,200          
Warrants Outstanding     4,500 6,400          
Private Warrant Exchange [Member] | Maximum [Member]                  
Equity and Equity Units Offering Disclosure [Line Items]                  
Exercise price of warrants, per share     $ 0.75 $ 1.00          
Share Price     0.60 0.80          
Private Warrant Exchange [Member] | Minimum [Member]                  
Equity and Equity Units Offering Disclosure [Line Items]                  
Exercise price of warrants, per share     0.30 0.30          
Share Price     $ 0.24 $ 0.24          
Private Warrant Exchange [Member] | Actual Shares [Member]                  
Equity and Equity Units Offering Disclosure [Line Items]                  
Common stock, par value $ 0.001       $ 0.001   $ 0.001    
Stock Issued During Period, Shares, Warrant Exercised 500   5,000 7,000          
Warrants Outstanding 500       500   500    
Common Stock [Member]                  
Equity and Equity Units Offering Disclosure [Line Items]                  
Number of shares to be sold           4,000      
Common Stock [Member] | Private Equity Offering [Member] | Unregistered Common Stock [Member]                  
Equity and Equity Units Offering Disclosure [Line Items]                  
Common stock, par value   $ 0.001              
Sale of common stock issue price per share   $ 1.50              
Shares issued during the period new issues shares   670              
Proceeds from issuance of common stock   $ 1,000