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Stock-Based Compensation (Schedule of Assumptions Used) (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Shareholder Value Awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend yield 2.50% 2.50% 2.50%
Risk-free interest rate 1.38% 2.46% 2.31%
Volatility 20.90% 21.00% 22.26%
Relative Value Awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend yield 2.50%    
Risk-free interest rate 1.38%    
Volatility 19.89%