Annual report pursuant to Section 13 and 15(d)

Share-based Compensation - Additional Information (Detail)

v3.10.0.1
Share-based Compensation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
May 26, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Total intrinsic value of stock options exercised $ 1.4 $ 0.7 $ 0.7  
Tax benefits realized from exercise of options and vesting of awards 2.9 5.8 1.6  
Restricted Stock [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Unrecognized compensation cost $ 2.4      
Weighted average period remaining 1 year 5 months 15 days      
Fair value of shares vested $ 3.7 3.9 2.9  
Restricted Stock [Member] | Non Employee Directors [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based payment award, award vesting period 1 year      
Restricted Stock [Member] | Minimum [Member] | Employees [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based payment award, award vesting period 1 year      
Restricted Stock [Member] | Maximum [Member] | Employees [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based payment award, award vesting period 3 years      
Performance Shares [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based payment award, award vesting period 2 years      
Unrecognized compensation cost $ 4.1      
Weighted average period remaining 1 year 5 months      
Fair value of shares vested $ 6.6 $ 9.9 $ 0.1  
Stock Options [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based payment award, award vesting period 3 years      
Maximum term of stock options 10 years      
Forfeiture period after date of termination 90 days      
Weighted-average grant date fair value (in dollars per share)   $ 12.38 $ 10.53  
Unrecognized compensation cost $ 0.3      
Weighted average period remaining 1 year      
2013 Omnibus Equity Incentive Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Common stock available for awards (in shares)       3,361,053
Shares available for future grants (in shares) 1,580,918