Annual report pursuant to Section 13 and 15(d)

Share-based Compensation - Summary of Stock Options Outstanding under Plans (Detail)

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Share-based Compensation - Summary of Stock Options Outstanding under Plans (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
2007 and 2013 Plan        
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]        
Options Outstanding, Number of Shares (shares) 156,438 338,338 364,088 387,901
Options Outstanding, Intrinsic Value $ 348      
Options Outstanding, Weighted-Average Exercise Price Per Share (in USD per share) $ 18.84 $ 17.52 $ 17.86 $ 17.49
Options Exercisable, Number of Shares (shares) 156,438 338,338 354,753  
Options Exercisable, Intrinsic Value $ 924      
Options Exercisable, Weighted-Average Exercise Price Per Share (in USD per share) $ 18.84 $ 17.52 $ 17.71  
Intrinsic value of stock options outstanding (in USD per share) 20.00      
$10.80 to $14.99        
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]        
Exercise Price Range, Lower Limit (in USD per share) 10.80      
Exercise Price Range, Upper Limit (in USD per share) $ 14.99      
$10.80 to $14.99 | 2007 and 2013 Plan        
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]        
Options Outstanding, Number of Shares (shares) 10,438      
Options Outstanding, Intrinsic Value $ 78      
Options Outstanding, Weighted-Average Exercise Price Per Share (in USD per share) $ 12.54      
Options Outstanding, Weighted-Average Remaining Contractual Life 2 years 10 months 24 days      
Options Exercisable, Number of Shares (shares) 10,438      
Options Exercisable, Intrinsic Value $ 78      
Options Exercisable, Weighted-Average Exercise Price Per Share (in USD per share) $ 12.54      
Options Exercisable, Weighted-Average Exercise Price Per Share (in USD per share) 2 years 10 months 24 days      
$15.00 to $19.99        
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]        
Exercise Price Range, Lower Limit (in USD per share) $ 15.00      
Exercise Price Range, Upper Limit (in USD per share) $ 19.99      
$15.00 to $19.99 | 2007 and 2013 Plan        
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]        
Options Outstanding, Number of Shares (shares) 85,000      
Options Outstanding, Intrinsic Value $ 270      
Options Outstanding, Weighted-Average Exercise Price Per Share (in USD per share) $ 16.82      
Options Outstanding, Weighted-Average Remaining Contractual Life 3 years 9 months 18 days      
Options Exercisable, Number of Shares (shares) 85,000      
Options Exercisable, Intrinsic Value $ 270      
Options Exercisable, Weighted-Average Exercise Price Per Share (in USD per share) $ 16.82      
Options Exercisable, Weighted-Average Exercise Price Per Share (in USD per share) 3 years 9 months 18 days      
$20.00 to $24.83        
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]        
Exercise Price Range, Lower Limit (in USD per share) $ 20.00      
Exercise Price Range, Upper Limit (in USD per share) $ 24.83      
$20.00 to $24.83 | 2007 and 2013 Plan        
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]        
Options Outstanding, Number of Shares (shares) 61,000      
Options Outstanding, Weighted-Average Exercise Price Per Share (in USD per share) $ 22.73      
Options Outstanding, Weighted-Average Remaining Contractual Life 4 years 9 months 18 days      
Options Exercisable, Number of Shares (shares) 61,000      
Options Exercisable, Weighted-Average Exercise Price Per Share (in USD per share) $ 22.73      
Options Exercisable, Weighted-Average Exercise Price Per Share (in USD per share) 4 years 9 months 18 days