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Debt - Unsecured Revolving Lines of Credit - Additional Information (Details) - USD ($)
$ in Millions
Sep. 30, 2021
Dec. 31, 2020
Feb. 28, 2018
Debt Instrument [Line Items]      
Maximum borrowing capacity $ 900.0    
Letters of credit, outstanding amount 19.7 $ 35.6  
Unsecured Debt      
Debt Instrument [Line Items]      
Maximum borrowing capacity 700.0    
Revolving Credit Facility      
Debt Instrument [Line Items]      
Maximum borrowing capacity 300.0    
Revolving Credit Facility | Unsecured Debt      
Debt Instrument [Line Items]      
Maximum borrowing capacity 50.0   $ 250.0
Core Portfolio | Revolving Credit Facility | Unsecured Debt      
Debt Instrument [Line Items]      
Debt available balance 193.1 101.1  
Credit facility amount outstanding 102.9 138.4  
Letters of credit, outstanding amount $ 4.0 $ 10.5