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Stock-Based Compensation - Additional Information (Detail)
$ / shares in Units, $ in Thousands
3 Months Ended
Aug. 31, 2017
USD ($)
$ / shares
shares
Non-Qualified Stock Options  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Non-qualified stock options, granted | shares 90,200
Non-qualified stock option, per share price | $ / shares $ 47.76
Non-qualified stock option, fair value, per share price | $ / shares $ 14.99
Pre-tax stock-based compensation | $ $ 1,203
Pre-tax stock-based compensation, period of recognition 3 years
Service-Based Restricted Common Shares  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Pre-tax stock-based compensation, period of recognition 3 years
Performance share awards granted | shares 122,400
Restricted common shares, fair value per share | $ / shares $ 47.81
Pre-tax stock-based compensation | $ $ 5,208
Performance Shares  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Pre-tax stock-based compensation, period of recognition 3 years
Performance share awards granted | shares 54,700
Pre-tax stock-based compensation | $ $ 2,768