Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Additional Information (Detail)

v3.10.0.1
Share-Based Compensation - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Share-based compensation expense $ 930,000 $ 670,000 $ 1,814,000 $ 1,363,000
Related tax benefits on non-qualified stock options $ 262,000 $ 274,000 $ 512,000 $ 550,000
Number of shares, stock options exercised (shares) 0 10,500 25,750 11,500
Stock option awards [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Unrecognized share-based compensation expense $ 0   $ 0  
Restricted stock awards [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Unrecognized share-based compensation expense $ 5,756,000   $ 5,756,000