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Shareholders' Equity - Additional Information (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Sep. 30, 1999
Stockholders Equity Note [Line Items]      
Preferred stock outstanding 0 0  
Number of shares authorized to be repurchased     7,500,000
Cost of repurchased shares $ 114,425 $ 114,425  
Remaining number of shares authorized to be repurchased 1,129,087    
Common Stock      
Stockholders Equity Note [Line Items]      
Amount of votes common stock is entitled One    
Percentage of Board entitled to elect 25.00%    
Treasury stock, shares 6,322,650 6,322,650  
Class B Common Stock      
Stockholders Equity Note [Line Items]      
Amount of votes common stock is entitled Ten    
Treasury stock, shares 48,263 48,263