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Share-Based Compensation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized compensation cost related to unvested share-based equity awards $ 93,119    
Weighted average period of recognition of unvested share-based equity awards (in years) 1 year 6 months 10 days    
Unrecognized compensation cost related to unvested share-based equity awards, Stock Options $ 31,087    
Unrecognized compensation cost related to unvested share-based equity awards, Restricted Stock $ 62,032    
Weighted average remaining contractual life of option outstanding 6 years 7 months 11 days    
Weighted average remaining contractual life of option exercisable 4 years 6 months 11 days    
Estimated weighted average fair value of options granted $ 18.45 $ 16.81 $ 37.64
Total intrinsic value of options exercised $ 57,400    
Total intrinsic value of options outstanding 176,289    
Total intrinsic value of options exercisable $ 78,131    
Weighted average fair values at the grant dates of grants awarded $ 82.14    
Omnibus Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Maximum number of shares of common stock available for issuance 21,000,000    
Omnibus Incentive Plan | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock option awards granted, vesting period 2 years    
Omnibus Incentive Plan | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock option awards granted, vesting period 4 years    
Omnibus Incentive Plan | Deferred Stock Units | Non-employee directors      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common stock shares granted 11,000 11,000 8,000
Omnibus Incentive Plan | Deferred Stock Units | Non-employee directors | Since 2007      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common stock shares granted 155,000    
Stock Option Plans      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common stock shares granted 1,267,812 1,326,430 743,062
Stock Option Plans | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock option awards granted, vesting period 3 years    
Stock Option Plans | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock option awards granted, expiration period 10 years    
Directors Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Maximum shares authorized for issuance 500,000    
Shares of common stock earned 73,000    
Additional shares issued to retired directors 427,000    
Liabilities under share plan $ 9,067 $ 6,111  
Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total intrinsic value of restricted stock expected to vest $ 145,823    
Weighted average fair values at the grant dates of grants awarded $ 85.97 $ 77.53 $ 139.50