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Share-Based Compensation (Details) - USD ($)
$ / shares in Units, $ 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]      
Compensation expense $ 2.7 $ 1.3 $ 2.9
Restricted Stock Units Equity Awards [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Nonvested awards January 1, 27,370 13,126  
Granted 20,472 15,931  
Vested (13,126) 0  
Undistributed vested awards [1] (1,249) (1,687)  
Nonvested awards December 31, 33,467 27,370 13,126
Unvested, weighted average grant date fair value per share, beginning balance $ 69.28 $ 65.83  
Granted, weighted average grant date fair value 69.95 72.46  
Vested, weighted average grant date fair value 65.83    
Undistributed vested awards, weighted average grant date fair value per share [1] 69.95 72.46  
Unvested, weighted average grant date fair value per share, ending balance $ 71.02 $ 69.28 $ 65.83
Restricted Stock Units Liability Awards [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Nonvested awards January 1, 0 6,064  
Granted 0 0  
Vested 0 (6,064)  
Undistributed vested awards [2] 0 0  
Nonvested awards December 31, 0 0 6,064
Performance Units Liability Awards [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Award vesting period 3 years    
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Nonvested awards January 1, 16,514 13,870  
Granted 11,320 10,395  
Vested (7,806) (6,064)  
Undistributed vested awards [3] (1,249) (1,687)  
Nonvested awards December 31, 18,779 16,514 13,870
Weighted average fair Value of each nonvested award $ 92.18 $ 76.87  
Weighted average estimated payout percent based on performance criteria 127.50% 109.20%  
Performance Units Liability Awards [Member] | Maximum [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Awards to be granted as percentage of target units 200.00%    
Performance Units Liability Awards [Member] | Minimum [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Awards to be granted as percentage of target units 0.00%    
2006 Performance Unit Plan [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Common stock to be issued with plan 0    
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Nonvested awards January 1, 2,004 5,760  
Granted 0 0  
Vested (2,004) (3,756)  
Nonvested awards December 31, 0 2,004 5,760
2006 Performance Unit Plan [Member] | Performance Shares [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Award vesting period 5 years    
2013 Director Incentive Agreement [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Common stock to be issued with plan 0    
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Nonvested awards January 1, 0 1,472  
Granted 0 0  
Vested 0 (1,472)  
Nonvested awards December 31, 0 0 1,472
2013 Director Incentive Agreement [Member] | Performance Shares [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Award vesting period 3 years    
2006 Performance Unit Plan and 2013 Director Incentive Plan [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Cash payments distributed related to awards previously granted and now payable $ 1.8    
2020 Performance Unit Plan [Member] | Restricted Stock Units Liability Awards [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Cash payments distributed related to awards previously granted and now payable 0.7    
2020 Performance Unit Plan [Member] | Performance Units Liability Awards [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Cash payments distributed related to awards previously granted and now payable $ 1.1    
Share Based Compensation Arrangement By Share Based Payment Award Payout Ratio 146.00%    
2021 Long Term Incentive Plan [Member] | Maximum [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Common stock to be issued with plan 500,000    
2021 Long Term Incentive Plan [Member] | Restricted Stock Units Equity Awards [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Award vesting period 3 years    
2021 Long Term Incentive Plan [Member] | Restricted Stock Units Liability Awards [Member]      
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]      
Award vesting period 3 years    
[1] Represents restricted stock units that vested but were not distributed to retirement-eligible employees.
[2] Represents restricted stock units that vested but were not distributed to retirement-eligible employees.
[3] Represents performance units that vested but were not distributed to retirement-eligible employees.