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Common Stock Repurchase Programs - Additional Information (Detail) - USD ($)
 1 Months Ended 12 Months Ended
Mar. 16, 2015
Dec. 17, 2014
Oct. 31, 2015
Jul. 31, 2015
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Mar. 31, 2015
Dec. 31, 2014
Oct. 31, 2014
Common Stock [Line Items]                    
Common stock repurchased         $ 70,192,000 $ 61,828,000 $ 235,051,000      
Common stock authorized for repurchase                   $ 600,000,000
Common Stock [Member]                    
Common Stock [Line Items]                    
Repurchased common stock, shares         1,038,000 946,000 3,365,000      
Common stock repurchased         $ 10,000 $ 9,000 $ 34,000      
Restricted Stock [Member]                    
Common Stock [Line Items]                    
Number of shares withheld to satisfy minimum statutory tax withholding obligations         38,257 46,490        
Amount withheld to satisfy minimum statutory tax withholding obligations         $ 2,100,000 $ 3,200,000        
Accelerated Share Repurchase (ASR) Agreements [Member]                    
Common Stock [Line Items]                    
Repurchased common stock, shares 2,200,000 2,500,000 300,000 300,000            
Common stock repurchased $ 200,000,000 $ 200,000,000                
Common stock purchase               $ 200,000,000 $ 200,000,000