Quarterly report pursuant to Section 13 or 15(d)

Investments In Unconsolidated Joint Ventures (Summary Of Company's Investment In Unconsolidated Joint Ventures) (Details)

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Investments In Unconsolidated Joint Ventures (Summary Of Company's Investment In Unconsolidated Joint Ventures) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2013
Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures $ 158,505 $ 132,339
Plaza VIII & IX Associates, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 4,022 4,321
South Pier At Harborside [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures (2,487) (1,225)
Red Bank Corporate Plaza, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 3,985 3,876
12 Vreeland Associates, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 12,748 12,840
Boston Downtown Crossing [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 13,012 13,012
Gale Jefferson, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures   1,029
Stamford SM LLC [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 34,547 34,006
Marbella RoseGarden, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 16,601 16,918
RoseGarden Monaco Holdings, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 4,363 4,761
Rosewood Lafayette Holdings, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 1,698 1,988
PruRose Port Imperial South 15, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures   606
Rosewood Morristown, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 6,935 7,091
Overlook Ridge, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 71 31
Overlook Ridge JV 2C/3B, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 91 179
Roseland/North Retail, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 2,112 2,161
BNES Associates III [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 1,839 1,955
Portside Master Company, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 3,637 3,651
PruRose Port Imperial South 13, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 2,817 2,920
Roseland/Port Imperial Partners, L.P. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 2,635 2,582
RoseGarden Marbella South, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 6,241 6,182
PruRose Riverwalk G, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 3,959 4,136
Elmajo Urban Renewal Associates, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 725 849
Riverpark At Harrison I, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 2,641 2,606
150 Main Street, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 2,602 2,395
RoseGarden Monaco, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 1,178 1,165
Hillsborough 206 Holdings, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 1,973 1,967
Grand Jersey Waterfront Urban Renewal Associates, L.L.C. [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures 337 337
Crystal House Apartments Investors LLC [Member]
   
Schedule of Equity Method Investments [Line Items]    
Company's investments in unconsolidated joint ventures $ 30,223