Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity, Stock Incentive Plan and Net Income per Share - Stock Option Activity (Details)

v3.20.4
Shareholders' Equity, Stock Incentive Plan and Net Income per Share - Stock Option Activity (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation $ 11,033 $ 11,715 $ 10,191
Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend yield (in hundredths) 1.10%   1.10%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate 24.10%   24.40%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate 1.50%   2.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term 5 years 10 months 24 days   6 years 1 month 6 days
Continuing Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at beginning of year (shares) 417 512 417
Granted (shares) 36   190
Exercise of stock options (in shares) (89) (87) (95)
Outstanding at end of year (shares) 359 417 512
Exercisable at end of year 265 262 213
Weighted Average Outstanding at beginning of year (per share) $ 53.37 $ 51.49 $ 44.55
Weighted average exercise price for options granted in the period 65.96   61.72
Weighted average exercise price for options exercised in the period 47.72 42.24 41.42
Weighted Average Outstanding at end of year (per share) 55.79 53.37 51.49
Weighted average exercise price for options exercisable at year end 53.20 $ 50.03 44.66
Weighted-average fair value of options granted during the year (dollars per share) $ 14.79   $ 15.82
Aggregate intrinsic value of options exercised $ 1,568 $ 2,196 $ 1,992
Average aggregate intrinsic value for options outstanding 970    
Average aggregate instrinsic value for exercisable options 1,435    
Share-based compensation 1,163 1,556 1,521
Tax benefit related to share-based compensation expense $ 287 $ 392 $ 384
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period 5 8  
Unrecognized compensation cost $ 784    
Weighted average period over which recognized compensation expense will be recognized (years) 1 year 3 months 18 days    
Weighted average exercise price for options forfeited in the period $ 59.73 $ 53.76  
Continuing Operations | Non-employee Director Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares available for grant 92    
Discontinued Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at beginning of year (shares) 14 26 22
Granted (shares)     4
Exercise of stock options (in shares)   (12)  
Outstanding at end of year (shares) 14 14 26
Exercisable at end of year 14 9 17
Weighted Average Outstanding at beginning of year (per share) $ 52.15 $ 49.00 $ 47.49
Weighted average exercise price for options granted in the period     58.40
Weighted average exercise price for options exercised in the period   45.46  
Weighted Average Outstanding at end of year (per share) 52.15 52.15 49.00
Weighted average exercise price for options exercisable at year end $ 52.15 $ 51.35 47.74
Weighted-average fair value of options granted during the year (dollars per share)     $ 16
Aggregate intrinsic value of options exercised   $ 193  
Average aggregate intrinsic value for options outstanding $ 54    
Average aggregate instrinsic value for exercisable options 54    
Share-based compensation 22 41 $ 57
Tax benefit related to share-based compensation expense $ 6 $ 11 $ 14
Exercise Price Range 43.67 through 44.90 [Member] | Continuing Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 59    
Exercisable at end of year 59    
Weighted Average Outstanding at end of year (per share) $ 43.70    
Weighted average exercise price for options exercisable at year end 43.70    
Range of exercise price, lower range limit 43.67    
Range of exercise price, upper range limit $ 44.90    
Weighted average remaining contractual life 2 years 1 month 6 days    
Exercise Price Range 47.82 through 48.32 [Member] | Continuing Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 68    
Exercisable at end of year 68    
Weighted Average Outstanding at end of year (per share) $ 47.86    
Weighted average exercise price for options exercisable at year end 47.86    
Range of exercise price, lower range limit 47.82    
Range of exercise price, upper range limit $ 48.32    
Weighted average remaining contractual life 3 years 1 month 6 days    
Exercise Price Range 50.71 through 53.73 [Member] | Continuing Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 26    
Exercisable at end of year 26    
Weighted Average Outstanding at end of year (per share) $ 51.31    
Weighted average exercise price for options exercisable at year end 51.31    
Range of exercise price, lower range limit 50.71    
Range of exercise price, upper range limit $ 53.73    
Weighted average remaining contractual life 1 year 7 months 6 days    
Exercise Price Range 57.18 through 60.42 [Member] | Continuing Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 70    
Exercisable at end of year 45    
Weighted Average Outstanding at end of year (per share) $ 58.73    
Weighted average exercise price for options exercisable at year end 58.64    
Range of exercise price, lower range limit 57.18    
Range of exercise price, upper range limit $ 60.42    
Weighted average remaining contractual life 4 years 1 month 6 days    
Exercise Price Range 64.26 through 65.96 [Member] | Continuing Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 136    
Exercisable at end of year 67    
Weighted Average Outstanding at end of year (per share) $ 64.71    
Weighted average exercise price for options exercisable at year end 64.26    
Range of exercise price, lower range limit 64.26    
Range of exercise price, upper range limit $ 65.96    
Weighted average remaining contractual life 5 years    
Exercise Price Range 43.67 through 65.96 [Member] | Continuing Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 359    
Exercisable at end of year 265    
Weighted Average Outstanding at end of year (per share) $ 55.88    
Weighted average exercise price for options exercisable at year end 53.23    
Range of exercise price, lower range limit 43.67    
Range of exercise price, upper range limit $ 65.96    
Weighted average remaining contractual life 3 years 8 months 12 days    
Exercise Price Range 47.82 through 58.40 | Discontinued Operations | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 14    
Exercisable at end of year 14    
Weighted Average Outstanding at end of year (per share) $ 52.22    
Weighted average exercise price for options exercisable at year end 52.22    
Range of exercise price, lower range limit 47.82    
Range of exercise price, upper range limit $ 58.40    
Weighted average remaining contractual life 3 years 6 months