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Stock-Based Compensation (Textuals) (Details) - USD ($)
shares in Millions, $ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Number of common stock shares which are authorized to issue awards 1.5    
Common Stock, Capital Shares Reserved for Future Issuance 0.1    
Shares available for future issuance 1.4    
Payout Percentage 100.00%    
Maximum [Member]      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Potential increase for payout percentage 200.00%    
Performance Shares [Member]      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Award service period 3 years    
Payout Percentage 132.70% 157.20% 173.20%
Total unrecognized compensation cost $ 16.6    
Weighted average period of recognition 2 years 3 months 18 days    
Estimated forfeiture rate 9.40%    
Restricted Stock Units [Member]      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Award service period 3 years    
Total unrecognized compensation cost $ 19.2    
Weighted average period of recognition 2 years 3 months 18 days    
Estimated forfeiture rate 14.30%    
Stock Appreciation Rights (SARs) [Member]      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Total unrecognized compensation cost $ 9.2    
Weighted average period of recognition 2 years 3 months 18 days    
Estimated forfeiture rate 11.80%    
Award expiration period 7 years