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Share-Based Compensation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended 48 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Unrecognized compensation cost related to unvested share-based equity awards $ 60,100     $ 60,100
Weighted average period of recognition of unvested share-based equity awards (in years) 1 year 14 days      
Unrecognized compensation cost related to unvested share-based equity awards, Stock Options $ 10,200     10,200
Unrecognized compensation cost related to unvested share-based equity awards, Restricted Stock $ 49,900     49,900
Weighted average remaining contractual life of option outstanding 5 years 2 months 1 day      
Weighted average remaining contractual life of option exercisable 3 years 10 months 2 days      
Estimated weighted average fair value of options granted $ 21.76 $ 19.54 $ 26.50  
Total intrinsic value of options exercised $ 13,400      
Total intrinsic value of options outstanding 35,600     35,600
Total intrinsic value of options exercisable $ 25,800     $ 25,800
Weighted average fair values at the grant dates of grants awarded $ 98.09 $ 96.38 $ 106.43  
Minimum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 0.00%      
Maximum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 200.00%      
Omnibus Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Maximum number of shares of common stock available for issuance 27,775,000     27,775,000
Omnibus Incentive Plan | Minimum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock option awards granted, vesting period 1 year      
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 20,000 15,000 12,000  
Additional shares issued to retired directors 13,000 14,000 10,000 48,000
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 216,000      
Stock Option Plans        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Common stock shares granted 606,060      
Directors Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Maximum shares authorized for issuance 500,000     500,000
Shares of common stock earned 73,000      
Additional shares issued to retired directors 427,000      
Liabilities under share plan $ 8,000 $ 11,000   $ 8,000
Performance Shares        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Granted 96,000      
Restricted Stock        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Granted 391,206      
Total intrinsic value of restricted stock expected to vest $ 108,200     $ 108,200
Weighted average fair values at the grant dates of grants awarded $ 92.23 $ 89.75 $ 114.42