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Stock-Based Compensation Plans (Details 5) - Performance awards - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Dividend yield (as a percent) 2.80% 3.10% 3.70%
Estimated volatility, minimum (as a percent) 11.10% 13.90% 11.80%
Estimated volatility, maximum (as a percent) 15.50% 18.80% 18.70%
Risk-free interest rate, minimum (as a percent) 1.45% 2.46% 1.86%
Risk-free interest rate, maximum (as a percent) 1.62% 2.57% 2.46%
Estimated performance award value based on total shareholder return measure (in dollars per share) $ 254.72 $ 204.15 $ 151.67
Historical volatility (as a percent) 50.00% 50.00% 50.00%
Implied volatility (as a percent) 50.00% 50.00% 50.00%
Market closing price (in dollars per share) $ 224.64 $ 195.86 $ 161.10