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Stock-Based Compensation (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation expense $ 6.5 $ 6.3 $ 3.9
Compensation expense tax (expense) benefit 0.2 0.3 0.4
Compensation expense not yet recognized for nonvested awards $ 4.9    
Nonvested awards, total compensation cost not yet recognized, period for recognition 2 years    
Shares vested in period, total fair value $ 4.2 $ 4.2 $ 3.7
Share-based Compensation, Significant Assumptions      
Risk-free interest rate 2.47% 2.30%  
Expected life, in years 3 years 3 years  
Expected volatility, minimum 16.40% 16.50%  
Expected volatility, maximum 20.90% 21.90%  
Dividend yield 3.50% 4.20%  
Performance Shares [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance and vesting period 3 years    
Performance Shares [Member] | Minimum [Member]      
Share-based Compensation, Significant Assumptions      
Percent of shares issued based on company performance 0.00%    
Performance Shares [Member] | Maximum [Member]      
Share-based Compensation, Significant Assumptions      
Percent of shares issued based on company performance 200.00%    
Share-based Payment Arrangement [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance and vesting period 1 year    
Share-based Payment Arrangement [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance and vesting period 5 years    
Executive retirement/retention program [Member] | Restricted Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance and vesting period 5 years 5 years  
Deferred Stock Unit [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Maximum percentage of compensation to be deferred 100.00%    
Maximum number of years for distribution payments 10    
Deferred stock units issued during period, shares 19,027 29,870 54,920
Deferred Compensation Arrangement with Individual, Shares Withdrawn 3,708    
Deferred stock units total compensation expense $ 3.7 $ 1.9 $ 2.9
Deferred Compensation Arrangement with Individual, Distribution Paid $ 0.3    
Common Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares available for grant 750,205