Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity - Narrative (Detail)

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Shareholders' Equity - Narrative (Detail)
 12 Months Ended
Feb. 24, 2016
USD ($)
shares
Dec. 31, 2017
USD ($)
shares
Dec. 31, 2016
shares
Dec. 31, 2015
shares
Stockholders Equity        
Amount authorized for stock repurchase program | $ $ 50,000,000      
Common stock reserved (in shares)   10,500,000    
Income tax effect recorded for currency translation adjustments | $   $ 0    
Convertible Class B Stock        
Stockholders Equity        
Class B stock voting rights per share   10    
Conversion ratio for Class B stock to common stock   1.00    
Treasury Stock        
Stockholders Equity        
Number of shares repurchased (in shares) 1,675,000 1,152,000 523,000 0
Treasury stock repurchased (in shares)   0