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Equity Compensation Plans - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Nov. 30, 2019
Nov. 30, 2018
Nov. 30, 2019
Nov. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Weighted-average fair value per share of stock options granted     $ 15.56  
Compensation expense related to share based awards $ 1,612,000 $ 3,155,000 $ 1,400,000 $ 2,831,000
Employee Stock Purchase Plan | 2011 Employee Stock Purchase Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Annual maximum limit percentage of compensation to purchase shares     5.00%  
Minimum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock option vesting period     3 years  
Stock option contractual terms     5 years  
Maximum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock option vesting period     5 years  
Stock option contractual terms     10 years