| Investments In Unconsolidated Joint Ventures (Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures) (Details) (USD $)In Thousands, unless otherwise specified
 | 3 Months Ended | 9 Months Ended | 
      
        | Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | $ (229) | $ 2,418 | $ (2,059) | $ 4,751 | 
      
        | Plaza VIII & IX Associates, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | 24 | 21 | 52 | 43 | 
      
        | South Pier At Harborside [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | 835 | 1,080 | 1,380 | 1,884 | 
      
        | Red Bank Corporate Plaza, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | 99 | 94 | 306 | 298 | 
      
        | 12 Vreeland Associates, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (25) | 279 | (1) | 603 | 
      
        | Boston Downtown Crossing [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures |  | (6) | 646 | (333) | 
      
        | Gale Jefferson, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures |  | 23 | 68 | 63 | 
      
        | Stamford SM LLC [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | 1,023 | 927 | 2,805 | 2,193 | 
      
        | Marbella RoseGarden, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (170) |  | (446) |  | 
      
        | RoseGarden Monaco Holdings, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (416) |  | (1,238) |  | 
      
        | Rosewood Lafayette Holdings, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (295) |  | (869) |  | 
      
        | PruRose Port Imperial South 15, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures |  |  | (606) |  | 
      
        | Rosewood Morristown, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (152) |  | (393) |  | 
      
        | Overlook Ridge JV 2C/3B, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | 53 |  | 204 |  | 
      
        | Roseland/North Retail, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (62) |  | (194) |  | 
      
        | BNES Associates III [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (37) |  | (108) |  | 
      
        | Portside Master Company, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (109) |  | (222) |  | 
      
        | PruRose Port Imperial South 13, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (181) |  | (459) |  | 
      
        | RoseGarden Marbella South, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (20) |  | (57) |  | 
      
        | PruRose Riverwalk G, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (198) |  | (576) |  | 
      
        | Elmajo Urban Renewal Associates, L.L.C. [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (87) |  | (255) |  | 
      
        | Estuary Urban Renewal Unit B, LLC [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (44) |  | (107) |  | 
      
        | Crystal House Apartments Investors LLC [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | (1,149) |  | (2,671) |  | 
      
        | Other [Member] |  |  |  |  | 
      
        | Schedule of Equity Method Investments [Line Items] |  |  |  |  | 
      
        | Company's equity in earnings of unconsolidated joint ventures | $ 682 |  | $ 682 |  |