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Shares Repurchased - Additional Information (Detail) - USD ($)
12 Months Ended
Apr. 27, 2016
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Apr. 11, 2018
Oct. 29, 2014
Class of Stock [Line Items]            
Repurchased common stock, value   $ 2,885,000 $ 7,891,000 $ 39,379,000    
Maximum [Member]            
Class of Stock [Line Items]            
Total Leverage Ratio         1.75%  
Three-Year Share Repurchase Program [Member]            
Class of Stock [Line Items]            
Common stock purchase authorized amount           $ 100,000,000
Share repurchase program, increase in authorized amount $ 60,000,000          
Share repurchase program, extended term date Apr. 27, 2019          
Repurchased common stock, shares   334,953,000 697,664,000 3,778,932,000    
Repurchased common stock, value   $ 2,885,000 $ 7,891,000 $ 39,379,000    
Dollar amount remaining available for future share repurchases   $ 85,729,000