Investments In Unconsolidated Joint Ventures (Summary Of The Results Of Operations) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Total revenues	$ 12,740	$ 17,474	$ 37,697	$ 56,938
Operating and other	(8,008)	(10,912)	(23,739)	(29,616)
Depreciation and amortization	(2,505)	(3,898)	(8,064)	(11,392)
Interest expense	(1,704)	(2,317)	(5,029)	(6,944)
Net income	523	347	865	8,986
Company's equity in earnings (loss) of unconsolidated joint ventures	539	475	1,174	213
Plaza VIII & IX Associates [Member]
Total revenues	272	221	721	673
Operating and other	(58)	(58)	(160)	(154)
Depreciation and amortization	(154)	(154)	(460)	(460)
Net income	60	9	101	59
Company's equity in earnings (loss) of unconsolidated joint ventures	31	5	51	30
Harborside South Pier [Member]
Total revenues	9,558	9,916	28,008	24,300
Operating and other	(6,296)	(6,751)	(18,860)	(17,627)
Depreciation and amortization	(1,415)	(1,307)	(4,254)	(3,742)
Interest expense	(1,112)	(1,134)	(3,357)	(3,320)
Net income	735	724	1,537	(389)
Company's equity in earnings (loss) of unconsolidated joint ventures	361	361	768	(267)
Red Bank Corporate Plaza [Member]
Total revenues	832	827	2,424	3,407
Operating and other	(231)	(263)	(601)	(694)
Depreciation and amortization	(226)	(225)	(677)	(676)
Interest expense	(167)	(83)	(376)	(252)
Net income	208	256	770	1,785
Company's equity in earnings (loss) of unconsolidated joint ventures	104	128	385	511
Gramercy Agreement [Member]
Total revenues	1,340	2,692	4,674	17,200
Operating and other	(968)	(1,464)	(2,860)	(4,453)
Depreciation and amortization	(449)	(1,106)	(1,781)	(3,058)
Interest expense	(384)	(606)	(1,167)	(1,887)
Net income	(461)	(484)	(1,134)	7,802
Princeton Forrestal Village [Member]
Total revenues		3,149		9,577
Operating and other		(1,954)		(5,515)
Depreciation and amortization		(790)		(2,509)
Interest expense		(422)		(1,274)
Net income		(17)		279
Company's equity in earnings (loss) of unconsolidated joint ventures		(11)		36
Gale Kimball [Member]
Total revenues		66		188
Net income		66		188
Company's equity in earnings (loss) of unconsolidated joint ventures		22		64
12 Vreeland [Member]
Total revenues	663	603	1,653	1,593
Operating and other	(93)	(57)	(145)	(147)
Depreciation and amortization	(261)	(316)	(892)	(947)
Interest expense	(41)	(72)	(129)	(211)
Net income	268	158	487	288
Company's equity in earnings (loss) of unconsolidated joint ventures	134	79	243	144
Boston-Downtown Crossing [Member]
Operating and other	(362)	(381)	(1,113)	(890)
Net income	(362)	(381)	(1,113)	(890)
Company's equity in earnings (loss) of unconsolidated joint ventures	(115)	(114)	(340)	(267)
Gale Jefferson [Member]
Total revenues	75		217
Operating and other		16		(136)
Net income	75	16	217	(136)
Company's equity in earnings (loss) of unconsolidated joint ventures	$ 24	$ 5	$ 67	$ (38)