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Debt - Unsecured Revolving Lines of Credit - Additional Information (Details) - USD ($)
Dec. 31, 2020
Dec. 31, 2019
Oct. 08, 2019
Feb. 20, 2018
Debt Instrument [Line Items]        
Maximum borrowing capacity     $ 750,000,000.0  
Letters of credit, outstanding amount $ 35,600,000 $ 19,800,000    
Unsecured Debt        
Debt Instrument [Line Items]        
Maximum borrowing capacity     600,000,000.0  
Revolving Credit Facility | Unsecured Debt        
Debt Instrument [Line Items]        
Maximum borrowing capacity     $ 250,000,000.0 $ 150,000,000.0
Core Portfolio | Revolving Credit Facility | Unsecured Debt        
Debt Instrument [Line Items]        
Debt available balance 101,100,000 173,600,000    
Maximum borrowing capacity 250,000,000.0      
Credit facility amount outstanding 138,400,000 60,800,000    
Letters of credit, outstanding amount $ 10,500,000 $ 15,600,000