Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.3
Share-Based Compensation - Summary of Stock Options Outstanding under Plans (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2019
Mar. 31, 2019
Jun. 30, 2018
Jun. 30, 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) 337,688 338,338   338,338    
Number of shares, Stock options exercised (shares) (1,250)   0 (1,900) (25,750)  
Number of Shares, Options outstanding at end of period (shares) 336,438 337,688   336,438   338,338
Number of Shares, Options exercisable at end of period (shares) 336,438     336,438    
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) $ 17.53 $ 17.52   $ 17.52    
Weighted-Average Exercise Price Per Share, Options exercised (in usd per share) 10.80     11.40    
Weighted-Average Exercise Price Per Share, Options outstanding at end of period (in usd per share) 17.55 $ 17.53   17.55   $ 17.52
Weighted-Average Exercise Price Per Share, Options exercisable at end of period (in usd per share) $ 17.55     $ 17.55    
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 4 months 24 days 4 years 7 months 6 days   4 years 4 months 24 days   4 years 7 months 6 days
Weighted-Average Remaining Contractual Life, Options exercised 0 years     1 year    
Weighted-Average Remaining Contractual Life, Options outstanding at end of period 4 years 4 months 24 days 4 years 7 months 6 days   4 years 4 months 24 days   4 years 7 months 6 days
Weighted-Average Remaining Contractual Life, Options exercisable at end of period 4 years 4 months 24 days          
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at beginning of period $ 1,356 $ 1,356   $ 1,356    
Aggregate Intrinsic Value of In-the-Money Options, Options exercised 0     18    
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at end of period 1,162 $ 1,356   1,162   $ 1,356
Aggregate Intrinsic Value of In-the-Money Options, Options exercisable at end of period $ 1,162     $ 1,162    
Intrinsic value represents the excess of the closing stock price related to options outstanding (in usd per share) $ 22.27 $ 21.27   $ 22.27   $ 19.70