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Share-based Compensation - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Increase in additional paid-in capital     $ 1,244,000  
Payments related to tax withholding for net-share settlement of share-based award $ 0 $ 0 $ 3,739,000  
Stock Option Awards        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock option awards granted 710,000 175,000 45,000  
Options outstanding, shares 1,480,000 992,000 886,000 1,323,000
Expected dividend yield 0.00% 0.00% 0.00%  
Deferred tax assets wrote off due to vested stock options not exercisable $ 0   $ 1,700,000  
Decrease in additional-paid in capital $ 0 $ 0 1,700,000  
Class A        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Increase in additional paid-in capital     $ 0  
2013 Equity Plan | Stock Option Awards        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock options vested 251,250 215,000 222,500  
Aggregate fair value of stock option vested $ 15,500,000 $ 13,000,000 $ 13,700,000  
Weighted average grant date fair value of stock option awards $ 51.68 $ 68.67 $ 75.54  
Share-based compensation expense recognized $ 14,600,000 $ 14,300,000 $ 11,800,000  
Unrecognized share-based compensation expense $ 33,800,000      
Unrecognized compensation expense expected to be recognized 3 years      
Increase in additional paid-in capital     1,200,000  
Payments related to tax withholding for net-share settlement of share-based award $ 0 0 3,700,000  
Adjustment to Additional paid in capital related to tax withholding for net-share settlement of share-based award $ 0 $ 0 $ 3,700,000  
2013 Equity Plan | Other Stock-based Awards        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period 4 years      
Share-based compensation expense recognized $ 0      
Unrecognized compensation expense expected to be recognized 3 years 4 months 24 days      
Unrecognized share-based compensation expense $ 400,000      
2013 Equity Plan | Class A        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation award expiration period 10 years      
Vesting period 4 years      
2013 Equity Plan | Class A | Stock Option Awards        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock option awards granted 710,000      
Options outstanding, shares 1,479,983      
2013 Equity Plan | Class A | Other Stock-based Awards        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Other stock-based awards granted 10,000      
Other stock-based awards granted weighted average exercise price per award $ 129.90      
2013 Equity Plan | Class A | Board of Directors        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation, stock authorized 2,300,000      
2013 Equity Plan | Class A | Employees, Officers, and Directors | Stock Option Awards        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares of class A common stock reserved and available for future issuance 566,250