Annual report pursuant to Section 13 and 15(d)

Organization And Basis Of Presentation (Narrative) (Details)

v3.20.4
Organization And Basis Of Presentation (Narrative) (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2020
USD ($)
ft²
property
item
state
Dec. 31, 2019
USD ($)
item
Dec. 19, 2019
ft²
Real Estate Properties [Line Items]      
Percentage of ownership interest 90.40% 90.40%  
Number of properties owned or investment interests 52    
Number of units | item 326 208  
Number of states where properties are located | state 3    
Consolidated joint ventures, total real estate assets | $ $ 486.1 $ 497.6  
Consolidated joint ventures, other assets | $ 4.5 5.5  
Consolidated joint ventures, mortgages | $ 284.8 283.7  
Consolidated joint ventures, other liabilities | $ 21.0 $ 18.9  
Increase in land and other impairments | $ $ 2.5    
Commercial Properties [Member]      
Real Estate Properties [Line Items]      
Number of tenants | item 225    
Multi-Family Properties [Member]      
Real Estate Properties [Line Items]      
Number of properties owned or investment interests 19    
Number of units | item 5,825    
Office [Member]      
Real Estate Properties [Line Items]      
Number of properties owned or investment interests 25    
Aggregate square feet of the property owned or investment interest | ft² 8,100,000    
Unconsolidated Joint Venture Office Buildings [Member]      
Real Estate Properties [Line Items]      
Number of properties owned or investment interests 2    
Aggregate square feet of the property owned or investment interest | ft² 200,000    
Area of property (in square feet) | ft² 200,000    
Unconsolidated Joint Venture Multi-Family Properties [Member]      
Real Estate Properties [Line Items]      
Number of properties owned or investment interests 6    
Number of units | item 1,786    
Unconsolidated Joint Venture Office/Flex Buildings And Hotel [Member]      
Real Estate Properties [Line Items]      
Number of properties owned or investment interests 3    
Number of units | item 723    
Parking/Retail [Member]      
Real Estate Properties [Line Items]      
Number of properties owned or investment interests 4    
Aggregate square feet of the property owned or investment interest | ft² 108,000    
Unconsolidated Joint Venture Parking/Retail Buildings [Member]      
Real Estate Properties [Line Items]      
Number of properties owned or investment interests 1    
Aggregate square feet of the property owned or investment interest | ft² 51,000    
Land [Member]      
Real Estate Properties [Line Items]      
Number of properties owned or investment interests 1    
Suburban Office Portfolio [Member]      
Real Estate Properties [Line Items]      
Area of property (in square feet) | ft²     6,600,000