Quarterly report pursuant to Section 13 or 15(d)

Investments In Unconsolidated Joint Ventures (Narrative) (Details)

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Investments In Unconsolidated Joint Ventures (Narrative) (Details)
$ in Thousands
 3 Months Ended
Mar. 31, 2018
USD ($)
ft²
property
item
Mar. 31, 2017
USD ($)
Dec. 31, 2017
USD ($)
Schedule of Equity Method Investments [Line Items]      
Carrying Value $ 249,513   $ 252,626
Number of units | item 365    
Area of mixed use project (in square feet) | ft² 81,700    
Amount outstanding $ 863,738   822,288
Management, leasing, development and other services fees 600 $ 900  
Accounts receivable due from unconsolidated joint ventures 500   $ 700
Maximum exposure to loss 164,600    
Estimated future funding commitments $ 36,000    
Unconsolidated Joint Venture Office Buildings [Member]      
Schedule of Equity Method Investments [Line Items]      
Number of properties | property 4    
Unconsolidated Joint Venture Office And Retail Buildings [Member]      
Schedule of Equity Method Investments [Line Items]      
Area of property (in square feet) | ft² 500,000    
Unconsolidated Joint Venture Retail Buildings [Member]      
Schedule of Equity Method Investments [Line Items]      
Number of properties | property 2    
Unconsolidated Joint Venture Multi-Family Properties [Member]      
Schedule of Equity Method Investments [Line Items]      
Number of properties | property 8    
Number of units | item 3,275    
Unconsolidated Joint Venture Hotel [Member]      
Schedule of Equity Method Investments [Line Items]      
Number of units | item 350    
Unconsolidated Joint Venture Development Projects [Member]      
Schedule of Equity Method Investments [Line Items]      
Number of units | item 419    
Unconsolidated Joint Venture Land Parcels [Member]      
Schedule of Equity Method Investments [Line Items]      
Number of units | item 3,738    
Unconsolidated Joint Ventures [Member] | Guarantee of Indebtedness of Others [Member]      
Schedule of Equity Method Investments [Line Items]      
Maximum borrowing capacity $ 318,000    
Amount outstanding 202,700    
Unconsolidated Joint Ventures [Member] | Parent Company [Member] | Guarantee of Indebtedness of Others [Member]      
Schedule of Equity Method Investments [Line Items]      
Maximum guaranteed amount 36,000    
Guaranteed amount $ 24,400    
Minimum [Member]      
Schedule of Equity Method Investments [Line Items]      
Percentage of interest in venture 12.50%    
Maximum [Member]      
Schedule of Equity Method Investments [Line Items]      
Percentage of interest in venture 85.00%    
Variable Interest Entity [Member]      
Schedule of Equity Method Investments [Line Items]      
Carrying Value $ 128,600    
Number of VIEs | property 4