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Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
 1 Months Ended
Feb. 24, 2017
Dec. 31, 2017
Dec. 31, 2016
Stock Repurchased During Period, Value $ 100.0    
Common Stock, Shares Authorized   200,000,000 200,000,000
Common Stock, Par or Stated Value Per Share   $ 0.01 $ 0.01
Stock Repurchase Program, Remaining Authorized Repurchase Amount   $ 52.9  
Unclassified Preferred Stock      
Preferred Stock, Shares Authorized   25,000,000