Quarterly report pursuant to Section 13 or 15(d)

Stock Grants to Employees (Detail)

v3.21.1
Stock Grants to Employees (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
1 Months Ended 3 Months Ended 9 Months Ended
Oct. 16, 2020
Sep. 30, 2020
Jul. 31, 2020
Jan. 28, 2020
Jul. 31, 2020
Aug. 31, 2020
Feb. 29, 2020
Feb. 28, 2021
Feb. 29, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock-based compensation               $ 9,053 $ 4,346
Common Stock                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock issued for incentive compensation and tendered for income tax , shares           323 380    
Treasury Stock                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock issued for incentive compensation and tendered for income tax , shares           156 127    
Chief Executive Officer [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock-based compensation     $ 1,600   $ 1,600        
Chief Executive Officer [Member] | Common Stock                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock issued for incentive compensation and tendered for income tax , shares     300            
Chief Executive Officer [Member] | Treasury Stock                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock issued for incentive compensation and tendered for income tax , shares     200            
Executive Officer [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock units granted, shares       11,700          
Share based compensation by share based payment arrangement vesting period       6 months          
Executives                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation by share based payment arrangement options granted during the period   3,350              
Chief Scientific Officer [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation by share based payment arrangement restricted stock shares granted during the period 200                
Share based compensation by share based payment arrangement vesting period 3 years                
Units granted, grant date fair value $ 2.81                
Performance Shares [Member] | Executives                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock units granted, shares   4,350              
Share based compensation by share based payment arrangement restricted stock shares granted during the period   4,350              
Stock Options                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation by share based payment arrangement options granted during the period               1,900  
Share based compensation by share based payment arrangement vesting period               3 years  
Stock Options | Executives                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation by share based payment arrangement options granted during the period   3,350              
Share based compensation by share based payment arrangement vesting period   3 years              
Restricted Stock Units (RSUs) [Member] | Executives                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock units granted, shares   1,120              
Share based compensation by share based payment arrangement restricted stock shares granted during the period   1,120              
Share based compensation by share based payment arrangement vesting period   3 years              
Units granted, grant date fair value   $ 3.12