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Share-Based Compensation Plans - Assumptions Used to Estimate Fair Value of Share Awards (Details) - Stock option
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Average risk-free interest rate (as a percent) 2.50% 2.60% 2.00%
Expected dividend yield (as a percent) 2.90% 1.60% 2.00%
Expected volatility (as a percent) 27.00% 27.00% 31.00%
Expected term (years) 6 years 6 years 6 years