Annual report pursuant to Section 13 and 15(d)

Equity Awards - Expense and unrecognized (Details)

v3.22.2.2
Equity Awards - Expense and unrecognized (Details) - USD ($)
$ in Thousands, shares in Millions
1 Months Ended 12 Months Ended
Jul. 31, 2020
May 31, 2022
May 31, 2021
May 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Compensation expense $ 1,600 $ 6,239 $ 10,429 $ 6,548
Surety Bond Backstop Agreement [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock based compensation   $ 6,600    
Common stock warrants to purchase shares   15    
Stock Options And Warrants [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vested during the period, grant date fair value   $ 3,900 4,700 3,300
Unrecognized compensation expense   $ 6,500    
Weighted average period over which unrecognized compensation expense is expected to be recognized   1 year 2 months 4 days    
Equity Instruments | General and Administrative Expenses        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Compensation expense   $ 6,200 $ 8,800 $ 6,500
Chief Executive Officer [Member] | Equity Instruments        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock based compensation   $ 1,600