Annual report pursuant to Section 13 and 15(d)

Stock Plans and Management Compensation (Details 1)

v3.24.0.1
Stock Plans and Management Compensation (Details 1) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of Shares Available for Grant (in shares) 3,600    
Non-Vested Stock Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Age of Grantee   62 years  
Share-Based Compensation Expense $ 20.4 $ 18.2 $ 16.3
Share-Based Compensation Expense, Tax Benefit 5.0 4.5 4.0
Fair Value of Shares Vested During the Period $ 24.5 $ 16.7 $ 11.3
Weighted Average Grant Date Fair Value $ 90.72 $ 82.14  
Awarded - Weighted Average Grant Date Fair Value 88.00 $ 93.62 $ 91.14
Forfeited - Weighted Average Grant Date Fair Value 86.54    
Vested - Weighted Average Grant Date Fair Value $ 68.17    
Share-Based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]      
Outstanding at January 1 601    
Awarded 278    
Forfeited (49)    
Vested (253)    
Outstanding at December 31 577 601  
Unrecognized Compensation Cost $ 14.2    
Non-Vested Stock Awards [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Age of Grantee plus Grantees Total Number of Years of Service 70 years    
Performance Shares [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-Based Compensation Expense $ 2.1 $ 3.6 $ 13.5
Share-Based Compensation Expense, Tax Benefit 0.5 0.9 3.3
Fair Value of Shares Vested During the Period $ 16.2 $ 14.6 $ 18.6
Weighted Average Grant Date Fair Value $ 90.09 $ 90.97  
Awarded - Weighted Average Grant Date Fair Value 78.49    
Forfeited - Weighted Average Grant Date Fair Value 87.15    
Vested - Weighted Average Grant Date Fair Value $ 77.02    
Share-Based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]      
Outstanding at January 1 191    
Awarded 206    
Forfeited (13)    
Vested (167)    
Outstanding at December 31 217 191  
Unrecognized Compensation Cost $ 1.3