Investments In Unconsolidated Joint Ventures (Summary Of Company's Investment In Unconsolidated Joint Ventures) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	$ 132,339	$ 32,015
Plaza VIII & IX Associates, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	4,321	4,291
South Pier At Harborside [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	(1,225)	(343)
Red Bank Corporate Plaza, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	3,876	3,676
12 Vreeland Associates, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	12,840	10,233
Boston Downtown Crossing [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	13,012	13,005
Gale Jefferson, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	1,029	1,153
Stamford SM LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	34,006
Marbella RoseGarden, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	16,918
RoseGarden Monaco Holdings, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	4,761
Rosewood Lafayette Holdings, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	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	7,091
Overlook Ridge, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	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	2,161
BNES Associates III [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	1,955
Portside Master Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	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	2,920
Roseland/Port Imperial Partners, L.P. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	2,582
RoseGarden Marbella South, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	6,182
PruRose Riverwalk G, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	4,136
Elmajo Urban Renewal Associates, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	849
Riverpark At Harrison I, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	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	1,165
Hillsborough 206 Holdings, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's investments in unconsolidated joint ventures	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	$ 337