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Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Schedule Of Equity [Line Items]    
Cash Dividend on Common Stock $ 0.80 $ 0.75
Aggregated Dividend Paid $ 40.9  
Dividend payable date declared Feb. 28, 2017  
Common stock Dividend Payable Date Apr. 14, 2017  
Dividend payable date of record Mar. 31, 2017  
2015 Stock Repurchase Program [Member]    
Schedule Of Equity [Line Items]    
Company repurchased, shares   0.5
Repurchase of Company stock for retirement   $ 24.8