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Share-Based Compensation - 2012 Equity Incentive Plan Narrative (Details) - 2021 Equity Incentive Plan - shares
6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
May 31, 2021
Class A common shares/units      
Class of Stock [Line Items]      
Number of shares available to grant (in shares)     9,544,095
Restricted share units      
Class of Stock [Line Items]      
Award vesting period 3 years 3 years  
Restricted share units | Non-Management Trustees      
Class of Stock [Line Items]      
Award vesting period 1 year    
Performance Share Units (PSU's)      
Class of Stock [Line Items]      
Award vesting period 3 years    
Service period 3 years    
Performance Share Units (PSU's) | Minimum      
Class of Stock [Line Items]      
Percentage of units expected to vest (in percent) 0.00%    
Performance Share Units (PSU's) | Maximum      
Class of Stock [Line Items]      
Percentage of units expected to vest (in percent) 200.00%