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Stock-Based Compensation - Valuation Assumptions (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
2020 PSU Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free rate 1.66%    
Dividend yield 2.80%    
Outperformance Program      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free rate   2.57% 2.37%
Dividend yield   3.00% 2.90%
Outperformance Program | One-Time Retention Awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free rate 1.63%    
Dividend yield 3.20%    
The Company | 2020 PSU Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected price volatility 17.00%    
The Company | Outperformance Program      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected price volatility   22.00% 20.00%
The Company | Outperformance Program | One-Time Retention Awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected price volatility 23.00%    
REIT Index | 2020 PSU Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected price volatility 14.00%    
REIT Index | Outperformance Program      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected price volatility   18.00% 18.00%
REIT Index | Outperformance Program | One-Time Retention Awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected price volatility 18.00%