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Stockholder's Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, shares in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2018
Oct. 31, 2018
Mar. 02, 2018
Dec. 31, 2017
Statement Of Shareholders Equity [Line Items]          
Effective portion of unrealized gain on derivative instruments $ 3,072,000 $ 3,072,000     $ 507,000
Stock repurchase program, authorized     $ 100,000,000    
Share repurchase, amount   $ 42,827,000      
2018 Stock Repurchase Plan [Member]          
Statement Of Shareholders Equity [Line Items]          
Common Stock Repurchase, Shares 380 793      
Stock repurchase program, authorized       $ 50,000,000  
Share repurchase, amount $ 18,200,000 $ 42,800,000      
Share repurchase, price per share $ 47.75 $ 53.96