Annual report pursuant to Section 13 and 15(d)

Organization And Basis Of Presentation (Details)

v3.6.0.2
Organization And Basis Of Presentation (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2016
USD ($)
ft²
state
property
item
Dec. 31, 2015
USD ($)
Real Estate Properties [Line Items]    
Percentage of ownership interest 89.50% 89.50%
Number of properties owned or investment interests 248  
Aggregate square feet of the property owned or investment interest | ft² 26,600,000  
Number of states where properties are located | state 6  
Consolidated joint ventures, total real estate assets | $ $ 201.9 $ 273.4
Consolidated joint ventures, mortgages | $ 78.4 89.5
Consolidated joint ventures, other liabilities | $ $ 19.2 $ 17.5
Commercial Properties [Member]    
Real Estate Properties [Line Items]    
Number of tenants | item 1,600  
Multi-Family Properties [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 19  
Number of units | item 5,614  
Office And Office/Flex Buildings [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 94  
Aggregate square feet of the property owned or investment interest | ft² 4,800,000  
Office [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 119  
Aggregate square feet of the property owned or investment interest | ft² 21,300,000  
Flex Properties [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 110  
Unconsolidated Joint Venture Office Buildings [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 36  
Aggregate square feet of the property owned or investment interest | ft² 5,600,000  
Industrial/Warehouse Facilities [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 6  
Aggregate square feet of the property owned or investment interest | ft² 387,400  
Unconsolidated Joint Venture Multi-Family Properties [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 10  
Number of units | item 3,587  
Unconsolidated Joint Venture Office/Flex Buildings And Hotel [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 1  
Parking/Retail [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 6  
Aggregate square feet of the property owned or investment interest | ft² 137,100  
Unconsolidated Joint Venture Parking/Retail 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 81,700  
Land [Member]    
Real Estate Properties [Line Items]    
Number of properties owned or investment interests 3