Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Plans (Details)

v3.10.0.1
Stock-Based Compensation Plans (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Mar. 01, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Mar. 01, 2018
May 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares available for issuance (in shares)   394,173        
Tax withholding associated with awards issued   $ 641 $ 500 $ 499    
Compensation expense not yet recognized   $ 1,500 $ 2,300      
Weighted average amortization period of compensation not yet recognized   1 year 9 months 24 days 1 year 8 months 9 days      
Restricted Stock            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock-based compensation expense   $ 2,885 $ 3,058 2,099    
Stock-based compensation included in costs and operating expenses   3,027 3,068 2,109    
Income tax benefit recognized for stock-based compensation   (755) (1,180) (811)    
Stock-based compensation expense, net of income tax benefit   2,272 1,888 1,298    
Restricted Stock | Non-employee Directors            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock-based compensation expense   553 642 544    
Restricted Stock | Employee            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock-based compensation expense   $ 2,332 $ 2,416 $ 1,555    
Restricted Stock Plan 2006            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares authorized (in shares)   1,000,000       500,000
Restricted Stock Plan 2006 | Non-employee Directors            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Restricted stock awarded (in shares)   11,200 16,100 17,600    
Stock-based compensation expense   $ 553 $ 642 $ 544    
Restricted Stock Plan 2006 | Employee            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Restricted stock awarded (in shares) 31,159          
Grant date fair value (in dollars per share) $ 47.14          
Vested award is paid in our shares 100.00%       100.00%  
Restricted Stock Plan 2006 | Restricted Stock            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Grant date fair value (in dollars per share)   $ 49.38 $ 39.85 $ 30.89