Quarterly report pursuant to Section 13 or 15(d)

Investments In Unconsolidated Joint Ventures (Roseland/Port Imperial Partners, L.P.) (Narrative) (Details)

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Investments In Unconsolidated Joint Ventures (Roseland/Port Imperial Partners, L.P.) (Narrative) (Details) (USD $)
6 Months Ended
Jun. 30, 2013
Oct. 23, 2012
item
Prudential [Member]
   
Schedule of Equity Method Investments [Line Items]    
Third party ownership percentage   79.00%
Capital balance $ 14,800,000  
Prudential-Port Imperial, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Third party ownership percentage   1.00%
Roseland/Port Imperial Partners, L.P. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Residual ownership interest   20.00%
Number of units   363
Percentage of operating return on capital 10.00%  
Percentage of return on additional capital contribution 10.00%  
Holding and distribution pattern under operating agreement The operating agreement of Roseland/PI provides, among other things, for the distribution of net cash flow to the members, as follows:to Prudential and Prudential LLC, in proportion to the excess of their operating return of ten percent on Prudential's Parcel C contribution, as defined, accrued to the date of such distribution over the aggregate amounts previously distributed to such partner for such return; to the partners, to the extent of any excess of such partner's operating return of ten percent on its additional capital contributions over the aggregate amounts previously distributed for such return; andto the partners in accordance with their percentage interests.  
Roseland/Port Imperial Partners, L.P. [Member] | Prudential And Prudential-Port Imperial, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Capital balance 394,000  
Roseland/Port Imperial Partners, L.P. [Member] | Parent Company [Member]
   
Schedule of Equity Method Investments [Line Items]    
Capital balance 98,000  
Roseland/Port Imperial Partners, L.P. [Member] | Land [Member] | Prudential And Prudential-Port Imperial, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Capital balance 58,100,000  
Roseland/Port Imperial Partners, L.P. [Member] | Land [Member] | Parent Company [Member]
   
Schedule of Equity Method Investments [Line Items]    
Capital balance 5,100,000  
Parcel C [Member] | Roseland/Port Imperial Partners, L.P. [Member] | Prudential And Prudential-Port Imperial, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Accumulated unpaid operating return 3,300,000  
Capital balance 18,200,000  
Parcel C [Member] | Roseland/Port Imperial Partners, L.P. [Member] | Parent Company [Member]
   
Schedule of Equity Method Investments [Line Items]    
Capital balance $ 8,000