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