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Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2018
Jun. 30, 2017
Equity [Abstract]      
Maximum shares authorized for repurchase, prior and new announcements and total after new announcement 50,000,000 50,000,000  
Stock repurchased, shares   800,000  
Shares repurchased, average price per share   $ 15.72  
Additional shares authorized for purchase 2,700,000 2,700,000  
Number of Options, exercised 0 24,000  
Exercise price of stock options, lower range limit   $ 15.29  
Exercise price of stock options, upper range limit   $ 18.97  
Proceeds from stock option exercises   $ 369 $ 1,722