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Shareholders' Equity - Additional Information (Detail)
 3 Months Ended 12 Months Ended
Oct. 30, 2017
Dec. 31, 2017
USD ($)
Vote
$ / shares
shares
Oct. 01, 2017
$ / shares
Dec. 31, 2016
$ / shares
shares
Apr. 03, 2016
$ / shares
Dec. 31, 2017
USD ($)
Vote
$ / shares
shares
Dec. 31, 2016
USD ($)
$ / shares
shares
Dec. 31, 2015
USD ($)
Oct. 31, 2017
$ / shares
Apr. 28, 2016
shares
Apr. 27, 2016
shares
Nov. 01, 2015
USD ($)
Aug. 03, 2015
USD ($)
Dec. 05, 2008
Right
Class of Stock [Line Items]                            
Authorized shares | shares   400,000       400,000                
Preferred stock Par value (in dollars per share) | $ / shares   $ 0.01       $ 0.01                
Common stock, shares authorized | shares   200,000,000   140,000,000   200,000,000 140,000,000     200,000,000 140,000,000      
Stock split 2                          
Common stock par value, in dollars per share | $ / shares   $ 0.002   $ 0.002   $ 0.002 $ 0.002   $ 0.002          
Vote entitled for each common share outstanding | Vote   1       1                
Number of preferred stock purchase right for dividend distribution | Right                           1
Outstanding common share to be acquiring person   15.00%       15.00%                
Stock Repurchased During Period, Value           $ 123,715,000 $ 47,149,000 $ 126,351,000            
Cash dividend declared per common share | $ / shares   $ 0.045 $ 0.043 $ 0.038 $ 0.04                  
Payments of Dividends           $ 29,037,000 $ 25,213,000              
Repurchase Program 2014 [Member]                            
Class of Stock [Line Items]                            
total shares repurchased | shares           2,670,000                
Stock Repurchased During Period, Shares | shares           1,592,000                
Stock Repurchased During Period, Value           $ 68,915,000                
Repurchase Program 2015 [Member]                            
Class of Stock [Line Items]                            
Repurchase of authorized common stock   $ 45,200,000       $ 45,200,000             $ 100,000,000  
Stock Repurchased During Period, Shares | shares           941,000                
Stock Repurchased During Period, Value           $ 54,800,000                
Repurchase Program November 2015 [Member]                            
Class of Stock [Line Items]                            
Repurchase of authorized common stock                       $ 100,000,000    
Common Stock [Member] | Repurchase Program 2014 [Member]                            
Class of Stock [Line Items]                            
Repurchased shares, total cost           $ 100,000,000