Quarterly report pursuant to Section 13 or 15(d)

Equity Awards and Warrants - Warrants (Details)

v3.21.2
Equity Awards and Warrants - Warrants (Details) - USD ($)
$ / shares in Units, $ in Thousands, shares in Millions
3 Months Ended
Aug. 31, 2021
Aug. 31, 2020
May 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Warrant exercises, value $ 503 $ 13,469  
Common Stock, Par or Stated Value Per Share $ 0.001   $ 0.001
Private Placement [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock issued via offering, tender or placement, value $ 2,872    
Private Warrant Exchange [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock issued via offering, tender or placement, shares 1.3    
Stock issued via offering, tender or placement, value $ 775 $ 7,804  
Maximum | Private Warrant Exchange [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Exercise price of warrants, per share $ 0.75    
Minimum | Private Warrant Exchange [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Exercise price of warrants, per share $ 0.45    
Compensatory Warrants [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Warrant exercises, value $ 500    
Exercise of warrants for cash, shares 0.7    
Compensatory Warrants [Member] | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Exercise price of warrants, per share $ 1.35    
Compensatory Warrants [Member] | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Exercise price of warrants, per share $ 0.45