Quarterly report pursuant to Section 13 or 15(d)

Investments In Unconsolidated Joint Ventures (Riverpark At Harrison I, L.L.C.) (Narrative) (Details)

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Investments In Unconsolidated Joint Ventures (Riverpark At Harrison I, L.L.C.) (Narrative) (Details) (USD $)
3 Months Ended
Mar. 31, 2013
Oct. 23, 2012
Schedule of Equity Method Investments [Line Items]    
Maximum borrowing capacity 600,000,000  
Riverpark At Harrison I, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Percentage of interest in venture   36.00%
Holding and distribution pattern under operating agreement In general, the operating agreement of Riverpark provides, among other things, for the distribution of net cash flow to the members in accordance with their ownership percentages.  
Riverpark At Harrison I, L.L.C. [Member] | Chall Enterprises, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Third party ownership percentage 36.00%  
Riverpark At Harrison I, L.L.C. [Member] | Investor Group [Member]
   
Schedule of Equity Method Investments [Line Items]    
Third party ownership percentage 28.00%  
Riverpark Project [Member]
   
Schedule of Equity Method Investments [Line Items]    
Percentage of capital required to fund project 40.50%  
Riverpark Project [Member] | Riverpark At Harrison I, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Number of units   141
Total project costs 24,200,000  
Construction Loan [Member] | Riverpark Project [Member] | Riverpark At Harrison I, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Maximum borrowing capacity 22,900,000