Quarterly report pursuant to Section 13 or 15(d)

Private Securities Offerings (Detail)

v3.21.1
Private Securities Offerings (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
3 Months Ended 6 Months Ended 9 Months Ended
Jan. 28, 2021
Dec. 08, 2020
Dec. 04, 2020
Nov. 17, 2020
Feb. 28, 2021
Feb. 29, 2020
Nov. 30, 2020
Feb. 28, 2021
Feb. 29, 2020
Oct. 26, 2020
May 31, 2020
Nov. 30, 2019
Aug. 31, 2019
Class of Stock [Line Items]                          
Stock price, in dollars per share           $ 0.50 $ 1.50   $ 0.50     $ 0.50 $ 0.50
Common stock, par value $ 0.001 $ 0.001 $ 0.001 $ 0.001 $ 0.001   $ 0.001 $ 0.001     $ 0.001    
Inducement interest expense         $ 4,139 $ 5,163   $ 11,242 $ 7,876        
Shares issued on conversion               8,300          
Private Placement [Member]                          
Class of Stock [Line Items]                          
Stock price, in dollars per share       $ 1.50                  
Shares issued during the period new issues shares       670                  
Proceeds from issuance of common stock       $ 1,000                  
Private Warrant Exchange [Member]                          
Class of Stock [Line Items]                          
Stock price, in dollars per share   0.24 0.36             $ 0.24      
Exercise price of warrants, per share   $ 0.30 $ 0.45                    
Shares issued during the period new issues shares 3,600 2,000 300   5,900   29,000            
Warrants exchanged (in shares) 2,500 1,900 300   4,700   27,900            
Proceeds from issuance of common stock $ 2,900 $ 400 $ 100       $ 12,400            
Inducement interest expense 3,400 $ 700 $ 100       $ 7,100            
Payments of Stock Issuance Costs $ 100                        
Private Warrant Exchange [Member] | Maximum                          
Class of Stock [Line Items]                          
Stock price, in dollars per share $ 0.75           $ 1.08            
Exercise price of warrants, per share 1.50           1.35            
Private Warrant Exchange [Member] | Minimum                          
Class of Stock [Line Items]                          
Stock price, in dollars per share 0.45           0.21            
Exercise price of warrants, per share $ 0.90           $ 0.30