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Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
9 Months Ended 113 Months Ended 122 Months Ended
Sep. 30, 2017
Dec. 31, 2016
Sep. 30, 2017
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Treasury stock, total repurchase during period (in shares)   10,488,000 10,873,000
Treasury stock, average price of share repurchased (in dollars per share)   $ 27.83 $ 27.76
Treasury stock, total cost of repurchased stock   $ 291.8 $ 301.8
Stock repurchase program, remaining amount available for repurchase $ 148.2   $ 148.2
Performance Shares | Minimum      
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Performance awards, percentage of grant available to vest 0.00%    
Performance Shares | Maximum      
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Performance awards, percentage of grant available to vest 100.00%    
Employee Stock Purchase Plan      
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Shares reserved for grant 443,000   443,000
2003 Plan | Employee Stock Option      
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Shares reserved for grant 1,100,000   1,100,000