Annual report pursuant to Section 13 and 15(d)

Investments In Unconsolidated Joint Ventures (Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures) (Details)

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Investments In Unconsolidated Joint Ventures (Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures [1] $ (6,081) $ 18,788 $ (3,172)
Amortization of basis difference 792 436 336
Unconsolidated Joint Venture Multi-Family Properties [Member] | Marbella RoseGarden, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures 334 231 231
Unconsolidated Joint Venture Multi-Family Properties [Member] | RoseGarden Monaco Holdings, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (265) (937) (1,224)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Rosewood Morristown, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (311) (317) (364)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverwalk G Urban Renewal, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures 196 (1,146) (955)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Crystal House Apartments Investors LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (923) (870) (123)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverpark At Harrison I, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (252) (190) (363)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverwalk C Urban Renewal, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (653) (58) (306)
Unconsolidated Joint Venture Multi-Family Properties [Member] | RoseGarden Marbella South, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures 93 (202)  
Unconsolidated Joint Venture Multi-Family Properties [Member] | Estuary Urban Renewal Unit B, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures     1
Unconsolidated Joint Venture Multi-Family Properties [Member] | Capitol Place Mezz LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (1,793) (2,440) (3,687)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Harborside Unit A Urban Renewal, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (6,356) (219)  
Unconsolidated Joint Venture Multi-Family Properties [Member] | Roseland/Port Imperial Partners, L.P. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (219) (62) (168)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Grand Jersey Waterfront URA, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (15) (80) (32)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Hillsborough 206 Holdings, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (25) (53) (5)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Plaza VIII & IX Associates, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures 386 393 344
Unconsolidated Joint Venture Office Buildings [Member] | Red Bank Corporate Plaza, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures 238 448 392
Unconsolidated Joint Venture Office Buildings [Member] | 12 Vreeland Associates, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures 496 347 270
Unconsolidated Joint Venture Office Buildings [Member] | BNES Associates III [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures 89 (15) 115
Unconsolidated Joint Venture Office Buildings [Member] | KPG-P 100 IMW JV, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures     (800)
Unconsolidated Joint Venture Office Buildings [Member] | Keystone-Penn [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures   600 3,812
Unconsolidated Joint Venture Office Buildings [Member] | Keystone-TriState [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures   (1,672) (2,182)
Unconsolidated Joint Venture Office Buildings [Member] | KPG-MCG Curtis JV, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (436) (92) 475
Unconsolidated Joint Venture Other Property [Member] | Roseland/North Retail, L.L.C. [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures (81) (52) (70)
Unconsolidated Joint Venture Other Property [Member] | South Pier At Harborside [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures [2] 3,277 24,180 3,036
Unconsolidated Joint Venture Other Property [Member] | Other [Member]      
Schedule of Equity Method Investments [Line Items]      
Company's equity in earnings of unconsolidated joint ventures $ 139 $ 994 $ (1,569)
[1] Amounts are net of amortization of basis differences of $792, $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.
[2] Equity in earnings in 2016 includes the effect of distributions received from the joint venture's refinancing. See Recent Joint Venture Transactions following in this footnote.