Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

v3.10.0.1
Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 3 Months Ended
Jun. 30, 2018
Jun. 30, 2018
May 24, 2018
May 08, 2018
Sep. 30, 2017
Schedule Of Stockholders Equity [Line Items]          
Repurchase of shares, price per share     $ 12.00    
Additional paid-in capital, exercise prices $ 242,493 $ 242,493     $ 142,385
Unvested Restricted Stock [Member]          
Schedule Of Stockholders Equity [Line Items]          
Common Stock, Shares, Outstanding 63,000 63,000      
2010 Non-Plan Stock Options Agreement Options [Member]          
Schedule Of Stockholders Equity [Line Items]          
Treasury shares issued, price per share $ 3.64        
Additional paid-in capital, exercise prices $ 4,400 $ 4,400      
Payroll tax liability $ 2,500 $ 2,500      
Class A Common Stock [Member]          
Schedule Of Stockholders Equity [Line Items]          
Common Stock, vote per share   One vote per share      
Common Stock, Shares, Outstanding 11,950,000 11,950,000     0
Repurchase of shares, price per share       $ 12.00  
Class A Common Stock [Member] | 2010 Non-Plan Stock Options Agreement Options [Member]          
Schedule Of Stockholders Equity [Line Items]          
Repurchase of shares, price per share $ 13.17 $ 13.17      
Class B Common Stock [Member]          
Schedule Of Stockholders Equity [Line Items]          
Common Stock, vote per share   Ten vote per share      
Common Stock, Shares, Outstanding 39,464,619 39,464,619 39,217,537 39,567,537 0
Class B Common Stock [Member] | 2010 Non-Plan Stock Options Agreement Options [Member]          
Schedule Of Stockholders Equity [Line Items]          
Stock option exercised, options 768,984        
Stock option exercised, price per share $ 5.70        
Repurchase of shares, shares 521,902        
Increase in class B common shares outstanding 247,082 247,082