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		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	$ (80)	$ 1,733	$ (1,830)	$ 2,333
Plaza VIII & IX Associates, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	19	12	28	22
South Pier At Harborside [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	1,056	792	545	804
Red Bank Corporate Plaza, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	106	101	207	204
12 Vreeland Associates, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	116	125	24	324
Boston Downtown Crossing [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	651	(227)	646	(327)
Gale Jefferson, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		20	68	40
Stamford SM LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	897	910	1,782	1,266
Marbella RoseGarden, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(165)		(276)
RoseGarden Monaco Holdings, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(423)		(822)
Rosewood Lafayette Holdings, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(284)		(574)
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	(117)		(241)
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	224		151
Roseland/North Retail, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(83)		(132)
BNES Associates III [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(2)		(71)
Portside Master Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(68)		(113)
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	(145)		(278)
RoseGarden Marbella South, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(19)		(37)
PruRose Riverwalk G, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(192)		(378)
Elmajo Urban Renewal Associates, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(82)		(168)
Estuary Urban Renewal Unit B, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(34)		(63)
Crystal House Apartments Investors LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	$ (1,535)		$ (1,522)