Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Share-Based Compensation - Summary of Stock Options Outstanding under Plans (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Mar. 31, 2019
Jun. 30, 2018
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]      
Number of Shares, Options outstanding at beginning of period (shares) 338,338    
Number of shares, Stock options exercised (shares) (650)    
Number of Shares, Options outstanding at end of period (shares) 337,688    
Number of Shares, Options exercisable at end of period (shares) 337,688    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]      
Weighted-Average Exercise Price Per Share, Options outstanding at beginning of period (in usd per share) $ 17.52    
Weighted-Average Exercise Price Per Share, Options exercised (in usd per share) 12.54    
Weighted-Average Exercise Price Per Share, Options outstanding at end of period (in usd per share) 17.53    
Weighted-Average Exercise Price Per Share, Options exercisable at end of period (in usd per share) $ 17.53    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term [Abstract]      
Weighted-Average Remaining Contractual Life, Options outstanding at beginning of period 4 years 7 months 6 days 4 years 10 months 24 days  
Weighted-Average Remaining Contractual Life, Options exercised 3 years 10 months 24 days    
Weighted-Average Remaining Contractual Life, Options outstanding at end of period 4 years 7 months 6 days 4 years 10 months 24 days  
Weighted-Average Remaining Contractual Life, Options exercisable at end of period 4 years 7 months 6 days    
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at beginning of period $ 1,213    
Aggregate Intrinsic Value of In-the-Money Options, Options exercised 5    
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at end of period 1,356    
Aggregate Intrinsic Value of In-the-Money Options, Options exercisable at end of period $ 1,356    
Intrinsic value represents the excess of the closing stock price related to options outstanding (in usd per share) $ 21.27   $ 19.70