Annual report pursuant to Section 13 and 15(d)

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

v3.19.3.a.u2
Shareholders' Equity, Stock Options and Net Income per Share - Employee Activity - Performance Shares (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Employee Activity - Performance Shares [Line Items]      
Share-based compensation $ 11,907 $ 10,549 $ 8,103
Key Employee Performance Share Based Plan [Member]      
Employee Activity - Performance Shares [Line Items]      
Share-based awards, vesting period 3 years    
Percentage of grant based on meeting EBITDA per share targets 50.00%    
Percentage of grant based on three year performance of Company's TSR as compared to TSR of peer group 50.00%    
Minimum percentage of shares attainable based on EBITDA per share targets 0.00%    
Maximum percentage of shares attainable based on EBITDA per share targets 200.00%    
Minimum percentage of shares attainable based on total shareholder return targets 0.00%    
Minimum percentage of peer group by which Company share price must outperform before incremental performance shares are issued 25.00%    
Maximum percentage of shares attainable based on total shareholder return targets 200.00%    
Percentage of Peer Group By Which Company Share Price Must Outperform Before Maximum Incremental Shares Are Issued 90.00%    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate 23.40% 24.30% 24.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate 2.50% 2.20% 1.40%
Outstanding at beginning of year (shares) 65 69 80
Granted (shares) 30 18 27
Vested (shares) (23)    
Forfeited (shares) (10) (22) (38)
Outstanding at end of year (shares) 62 65 69
Weighted average grant date fair value of non-vested shares at beginning of year $ 58 $ 58 $ 55
Weighted average fair value of performance shares 61 72 56
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value 64    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value 63 67 51
Weighted average grant date fair value non-vested shares at end of year $ 62 $ 58 $ 58
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Total Fair Value $ 3,870 $ 3,795 $ 3,980
Share-based compensation 1,176 1,263 1,045
Tax benefit related to share-based compensation expense 296 $ 318 $ 371
Unrecognized compensation cost $ 1,529    
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 1 year 9 months 18 days