| Investments In Unconsolidated Joint Ventures (Summary Of Company's Investment In Unconsolidated Joint Ventures) (Details) (USD $)In Thousands, unless otherwise specified
 | Sep. 30, 2013 | Dec. 31, 2012 | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | $ 131,859 | $ 132,339 | 
      
        | Plaza VIII & IX Associates, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 4,065 | 4,321 | 
      
        | South Pier At Harborside [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | (2,095) | (1,225) | 
      
        | Red Bank Corporate Plaza, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 3,972 | 3,876 | 
      
        | 12 Vreeland Associates, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 5,439 | 12,840 | 
      
        | Boston Downtown Crossing [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures |  | 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 | 35,667 | 34,006 | 
      
        | Marbella RoseGarden, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 15,976 | 16,918 | 
      
        | RoseGarden Monaco Holdings, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 3,524 | 4,761 | 
      
        | Rosewood Lafayette Holdings, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 1,119 | 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 | 6,603 | 7,091 | 
      
        | Overlook Ridge JV, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 178 | 31 | 
      
        | Overlook Ridge JV 2C/3B, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures |  | 179 | 
      
        | Roseland/North Retail, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 1,967 | 2,161 | 
      
        | BNES Associates III [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 1,708 | 1,955 | 
      
        | Portside Master Company, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 3,449 | 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 | 2,451 | 2,920 | 
      
        | Roseland/Port Imperial Partners, L.P. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 2,755 | 2,582 | 
      
        | RoseGarden Marbella South, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 7,160 | 6,182 | 
      
        | PruRose Riverwalk G, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 3,515 | 4,136 | 
      
        | Elmajo Urban Renewal Associates, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 232 | 629 | 
      
        | Estuary Urban Renewal Unit B, LLC [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 74 | 220 | 
      
        | RiverPark At Harrison I, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 3,404 | 2,606 | 
      
        | 150 Main Street, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures |  | 2,395 | 
      
        | RoseGarden Monaco, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 1,208 | 1,165 | 
      
        | Hillsborough 206 Holdings, L.L.C. [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 1,989 | 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 | 397 | 337 | 
      
        | Crystal House Apartments Investors LLC [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | 26,928 |  | 
      
        | Other [Member] |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  | 
      
        | Company's investments in unconsolidated joint ventures | $ 174 |  |