XML 50 R38.htm IDEA: XBRL DOCUMENT v3.10.0.1
Share-based Compensation - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2018
Jun. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Stock Option Awards          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock option awards granted 75,000        
Options outstanding, shares 1,490,000 1,481,000   1,490,000  
2013 Equity Plan | Stock Option Awards          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock option awards granted     0    
Stock options vested 15,000        
Aggregate fair value of stock option vested $ 1,200,000        
Weighted average grant date fair value of stock option awards $ 50.57        
Share-based compensation expense recognized $ 3,000,000   $ 3,700,000 $ 11,100,000 $ 10,600,000
Unrecognized share-based compensation expense 35,100,000     $ 35,100,000  
Unrecognized compensation expense expected to be recognized       3 years 1 month 6 days  
2013 Equity Plan | Other Stock-based Awards          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense recognized 0     $ 0  
Unrecognized compensation expense expected to be recognized       3 years 8 months 12 days  
Vesting period       4 years  
Unrecognized share-based compensation expense $ 500,000     $ 500,000  
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     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 556,250     556,250  
Stock option awards granted 75,000        
Options outstanding, shares 1,489,983     1,489,983