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Capital Stock - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2017
USD ($)
Vote
$ / shares
shares
Dec. 31, 2016
USD ($)
$ / shares
shares
Dec. 31, 2015
USD ($)
shares
Aug. 31, 2014
USD ($)
Components Of Common Stock [Line Items]        
Authorized capital, shares (in shares) | shares 243,000,000      
Common stock, par value (in dollars per share) | $ / shares $ 0.01 $ 0.01    
Common stock, shares authorized (in shares) | shares 240,000,000 240,000,000    
Preferred stock, shares authorized (in shares) | shares 3,000,000 3,000,000    
Common stock, voting rights description The holders of common stock are entitled to one vote for each share of common stock on all matters submitted to a vote of the Company’s shareholders.      
Common stock, votes per share | Vote 1      
Stock repurchase program, authorized amount | $       $ 50,000,000
Stock repurchased, average cost per share (in dollars per share) | $ / shares $ 10.82      
Acquisition of treasury stock | $ $ 16,617,000 $ 5,144,000 $ 1,960,000  
Shares Paid for Tax Withholding for Share Based Compensation, Value | $ 6,617,000      
Amount remaining under repurchase authorization | $ $ 25,266,000      
Treasury Stock        
Components Of Common Stock [Line Items]        
Acquisition of treasury stock (in shares) | shares 1,536,000 572,000 217,000  
Acquisition of treasury stock | $ $ 16,617,000 $ 5,144,000 $ 1,960,000  
Seriesa Junior Participating Preferred        
Components Of Common Stock [Line Items]        
Preferred stock, shares authorized (in shares) | shares 240,000      
Preferred stock, voting rights description each share of Series A Junior Participating Preferred Stock would entitle the holder thereof to 1,000 votes on all matters submitted to a vote of the shareholders of the Company      
Preferred stock, votes per share | Vote 1,000