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Stock-Based Compensation Plans (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2022
Sep. 30, 2021
Dec. 31, 2021
Jan. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common stock available under stock option plan (in shares) 9,733,171   9,733,171      
Vesting period     3 years      
Options, outstanding, number (in shares) 114,943   114,943      
Options, grants in period, gross (in shares)     0 0    
Plan 2020            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Number of shares authorized to issue under share based compensation plans (in shares)           12,500,000
Restricted Stock            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Share-based compensation arrangement age requirement to vest over original vesting period     55 years      
Time in service requirement to vest over original vesting period     10 years      
Nonvested awards, compensation cost not yet recognized $ 26.5   $ 26.5   $ 24.2  
Nonvested awards, compensation cost not yet recognized, period for recognition     1 year      
Equity instruments other than options, vested in period, fair value 0.1 $ 0.2 $ 22.6 $ 24.6    
Allocated share-based compensation expense, net of tax 5.3 5.5 18.4 18.2    
Allocated share-based compensation expense $ 6.9 $ 7.1 $ 23.8 $ 23.6    
Equity instruments other than options, nonvested, number (in shares) 1,881,445   1,881,445   1,671,011  
Performance Shares            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Nonvested awards, compensation cost not yet recognized, period for recognition     36 months      
Equity instruments other than options, nonvested, number (in shares) 481,000   481,000      
Total shareholder return performance measure, as a percentage 15.00%   15.00%      
Estimated vesting of shares based on performance shares (in shares) 410,000   410,000      
Minimum | Performance Shares            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options, vested and expected to vest, exercisable, number (in shares) 0   0      
Minimum | Performance Shares | Issue Date 2020            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Award vesting rights, percentage     0.00%      
Maximum | Performance Shares            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options, vested and expected to vest, exercisable, number (in shares) 1,059,000   1,059,000      
Maximum | Performance Shares | Issue Date 2020            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Award vesting rights, percentage     200.00%      
Maximum | Performance Shares | Issue Date 2022 And 2021            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Award vesting rights, percentage     230.00%