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Share-Based Compensation - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of common stock registered for award 61,600,000    
Number of additional common stock expect to register for award 10,000,000    
Shares available for future grants 13,100,000    
Vesting period 4 years    
Maximum contractual life 10 years    
Unrecognized share-based payment expense $ 53.0    
Weighted average period expected to be recognized 2 years 10 months 24 days    
Stock Options [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Requisite service period for stock award 1 year    
Stock Options [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Requisite service period for stock award 4 years    
RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted average period expected to be recognized 2 years 6 months    
Estimated outstanding RSU 1,044,000    
Unrecognized share-based payment expense related to nonvested stock options $ 49.4    
Fair value of RSUs vesting during the year $ 25.5 $ 40.6 $ 29.3
RSUs [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 2 years    
Requisite service period for stock award 1 year    
RSUs [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 4 years    
Requisite service period for stock award 4 years