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Share-Based Compensation - Assumptions Used in the Determination of Grant-Date Fair Value of Awards (Details) - TSR Stock Awards [Member] - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Grant date market value of a common share $ 49.24 $ 40.95 $ 44.07
Risk-free interest rate, minimum 2.59% 2.32% 1.57%
Risk-free interest rate, maximum 2.66% 2.68% 2.22%
Dividend yield 3.09% 3.52% 3.27%
Derived vesting period of TSR Restricted Stock and TSR LTIP I units 3 years 4 months 24 days 3 years 4 months 24 days 3 years 4 months 24 days
Weighted average expected term of TSR Stock Options and LTIP II units 5 years 9 months 18 days 5 years 7 months 6 days 5 years 9 months 18 days
Minimum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected volatility 19.08% 17.64% 21.33%
Maximum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected volatility 19.24% 18.02% 23.00%