Annual report pursuant to Section 13 and 15(d)

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

v3.20.4
Shareholders' Equity, Stock Incentive Plan and Net Income per Share - Employee Activity - Performance Shares (Details) - USD ($)
$ / shares in Units, shares in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Employee Activity - Performance Shares [Line Items]      
Share-based compensation $ 11,033,000 $ 11,715,000 $ 10,191,000
Key Employee Performance Share Based Plan [Member]      
Employee Activity - Performance Shares [Line Items]      
Share-based awards, vesting period 3 years    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate 23.50% 23.40% 24.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate 1.40% 2.50% 2.20%
Minimum percentage of shares attainable $ 0    
Maximum percentage of shares attainable $ 2    
Key Employee Performance Share Based Plan [Member] | Continuing Operations      
Employee Activity - Performance Shares [Line Items]      
Outstanding at beginning of year (shares) 58 62 66
Granted (shares) 38 28 17
Additional shares awarded based on performance 13    
Vested (shares) (33) (22)  
Forfeited (shares) (11) (10) (21)
Outstanding at end of year (shares) 65 58 62
Weighted average grant date fair value of non-vested shares at beginning of year $ 62.44 $ 58.40 $ 57.63
Weighted average fair value of performance shares 69.15 61.42 72.30
Stock Issued During Period, Weighted Average Grant Date Fair Value 51.13    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value 51.13 63.57  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value 66.37 62.77 67.28
Weighted average grant date fair value non-vested shares at end of year $ 67.62 $ 62.44 $ 58.40
Share-based compensation $ 1,242,000 $ 1,103,000 $ 1,208,000
Tax benefit related to share-based compensation expense 306,000 $ 278,000 $ 304,000
Unrecognized compensation cost $ 2,095,000    
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 1 year 10 months 24 days    
Key Employee Performance Share Based Plan [Member] | Discontinued Operations      
Employee Activity - Performance Shares [Line Items]      
Outstanding at beginning of year (shares) 4 3 3
Granted (shares) 1 2 1
Additional shares awarded based on performance 1    
Vested (shares) (2) (1)  
Forfeited (shares) (4)   (1)
Outstanding at end of year (shares)   4 3
Weighted average grant date fair value of non-vested shares at beginning of year $ 62.05 $ 57.90 $ 57.03
Weighted average fair value of performance shares 69.15 61.03 72.30
Stock Issued During Period, Weighted Average Grant Date Fair Value 51.13    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value 51.13 63.57  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value $ 65.69   67.28
Weighted average grant date fair value non-vested shares at end of year   $ 62.05 $ 57.90
Share-based compensation $ (8,000) $ 73,000 $ 55,000
Tax benefit related to share-based compensation expense $ (2,000) $ 18,000 $ 14,000