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Stockholders' Equity - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Oct. 19, 2016
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Compensation expense   $ 2,700,000 $ 3,200,000    
Unrecognized compensation cost   $ 7,000,000   $ 7,000,000  
Weighted average remaining period   3 years      
Fair market value of the restricted shares   $ 3,800,000      
Stock repurchase program, expiration period Dec. 31, 2019        
Repurchased shares of common stock   0      
Cash dividends declared (in USD per share)   $ 0.17 $ 0.17 $ 0.34 $ 0.32
Maximum [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock repurchase program, authorized amount $ 30,000,000        
2004 Plan [Member] | Restricted Stock [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares subject to outstanding awards (in shares)   750,576   750,576  
2014 Plan [Member] | Restricted Stock [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares of common stock available for delivery pursuant to the grant of awards (in shares)   750,000   750,000  
Additional shares of common stock available for grant       750,000  
Restricted shares for vesting period       5 years