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Stock-Based Compensation (Stock-Based Compensation Costs) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Share-Based Payment Arrangement, Noncash Expense [Abstract]      
Stock or Unit Option Plan Expense $ 0.0 $ 0.1 $ 0.1
Stock Appreciation Rights Expense 1.0 0.9 11.6
Allocated Share-based Compensation Expense 2.3 1.9 12.2
Share-based Payment Arrangement, Expense, Tax Benefit (0.3) (0.2) (1.5)
Restricted Stock Units (RSUs) [Member]      
Share-Based Payment Arrangement, Noncash Expense [Abstract]      
Restricted Stock or Unit Expense 0.9 0.7 0.5
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted Stock or Unit Expense 0.9 0.7 0.5
Restricted Stock      
Share-Based Payment Arrangement, Noncash Expense [Abstract]      
Restricted Stock or Unit Expense 0.4 0.2 0.0
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted Stock or Unit Expense $ 0.4 $ 0.2 $ 0.0