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) (USD $)
Sep. 30, 2013
property
Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]    
Investments in unconsolidated joint ventures $ 131,859,000 $ 132,339,000
Accounts receivable from unconsolidated joint ventures 856,000 370,000
Number of VIEs 5  
Maximum exposure to loss 13,700,000  
Estimated future funding commitments 3,100,000  
Unconsolidated Joint Venture Office Buildings [Member]
    
Schedule of Equity Method Investments [Line Items]    
Number of properties 20  
Unconsolidated Joint Venture Office And Retail Buildings [Member]
    
Schedule of Equity Method Investments [Line Items]    
Area of property (in square feet) 2,300,000  
Unconsolidated Joint Venture Retail Buildings [Member]
    
Schedule of Equity Method Investments [Line Items]    
Number of properties 2  
Unconsolidated Joint Venture Multi-Family Properties [Member]
    
Schedule of Equity Method Investments [Line Items]    
Number of properties 7  
Number of units 2,597  
Unconsolidated Joint Venture Hotel [Member]
    
Schedule of Equity Method Investments [Line Items]    
Number of units 350  
Unconsolidated Joint Venture Commercial Property [Member]
    
Schedule of Equity Method Investments [Line Items]    
Area of property (in square feet) 1,700,000  
Unconsolidated Joint Venture Development Projects [Member]
    
Schedule of Equity Method Investments [Line Items]    
Number of units 2,631  
Minimum [Member]
    
Schedule of Equity Method Investments [Line Items]    
Percentage of interest in venture 7.50%  
Maximum [Member]
    
Schedule of Equity Method Investments [Line Items]    
Percentage of interest in venture 80.00%  
Variable Interest Entity [Member]
    
Schedule of Equity Method Investments [Line Items]    
Investments in unconsolidated joint ventures $ 10,700,000  
Apartments [Member] | Unconsolidated Joint Venture Land Parcels [Member]
    
Schedule of Equity Method Investments [Line Items]    
Number of units 3,708  
Office [Member] | Unconsolidated Joint Venture Land Parcels [Member]
    
Schedule of Equity Method Investments [Line Items]    
Area of property (in square feet) 1,200,000