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Stock-Based Compensation - Additional Information (Detail) - USD ($)
$ in Millions
1 Months Ended 9 Months Ended
May 31, 2017
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Aggregate intrinsic value of options exercised in period   $ 46.1
Fair value of options vested in period   4.8
Employee Stock Option    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Unrecognized stock-based compensation expense   $ 10.6
Unrecognized stock-based compensation expense, estimated weighted-average recognition period   2 years 4 months 25 days
Restricted Stock Units    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Unrecognized stock-based compensation expense   $ 38.5
Unrecognized stock-based compensation expense, estimated weighted-average recognition period   2 years
Restricted share unit issued   295,000
Performance Based Restricted Stock Units    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted share unit issued 159,000