Segment Reporting (Schedule Of Segment Reporting Information, By Segment) (Details) (USD $) In Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010		Dec. 31, 2010
Total revenues	$ 177,155		$ 197,956		$ 544,592		$ 595,324
Total operating and interest expenses	105,113	[1],[2]	134,872	[2],[3]	337,903	[2],[4]	401,077	[2],[5]
Equity in earnings (loss) of unconsolidated joint ventures	539		475		1,174		213
Net operating income	72,581	[1],[6]	63,559	[3],[6]	207,863	[4],[6]	194,460	[5],[6]
Total assets	4,309,872				4,309,872				4,362,466
Total long-lived assets	4,047,921	[7]			4,047,921	[7]			4,098,872	[7]
Depreciation and amortization	48,498		47,978		144,914		143,942
Real Estate [Member]
Revenue for reportable segment	174,212		181,030		533,509		546,382
Operating and interest expenses for reportable segment	62,192	[2]	73,433	[2]	207,509	[2]	213,139	[2]
Equity in earnings (loss) of unconsolidated joint ventures for reportable segment	539		475		1,174		213
Net operating income for reportable segment	112,559	[6]	108,072	[6]	327,174	[6]	333,456	[6]
Total assets for reportable segment	4,291,958				4,291,958				4,332,408
Total long-lived assets for reportable segment	4,045,531	[7]			4,045,531	[7]			4,096,242	[7]
Construction Services [Member]
Revenue for reportable segment	2,406		16,733		9,225		50,173
Operating and interest expenses for reportable segment	2,681	[2]	16,629	[2]	10,066	[2]	49,723	[2]
Net operating income for reportable segment	(275)	[6]	104	[6]	(841)	[6]	450	[6]
Total assets for reportable segment	5,799				5,799				13,929
Corporate & Other [Member]
Revenue for reportable segment	537	[8]	193	[8]	1,858	[8]	(1,231)	[8]
Operating and interest expenses for reportable segment	40,240	[2],[8]	44,810	[2],[8]	120,328	[2],[8]	138,215	[2],[8]
Net operating income for reportable segment	(39,703)	[6],[8]	(44,617)	[6],[8]	(118,470)	[6],[8]	(139,446)	[6],[8]
Total assets for reportable segment	12,115	[8]			12,115	[8]			16,129	[8]
Total long-lived assets for reportable segment	$ 2,390	[7],[8]			$ 2,390	[7],[8]			$ 2,630	[7],[8]

[1] Excludes $48,498 of depreciation and amortization.

[2] Total operating and interest expenses represent the sum of: real estate taxes; utilities; operating services; direct construction costs; real estate services salaries, wages and other costs; general and administrative and interest expense (net of interest income). All interest expense, net of interest income, (including for property-level mortgages) is excluded from segment amounts and classified in Corporate & Other for all periods.

[3] Excludes $47,978 of depreciation and amortization.

[4] Excludes $144,914 of depreciation and amortization.

[5] Excludes $143,942 of depreciation and amortization.

[6] Net operating income represents total revenues less total operating and interest expenses [as defined in Note (a)], plus equity in earnings (loss) of unconsolidated joint ventures, for the period.

[7] Long-lived assets are comprised of net investment in rental property, unbilled rents receivable and investments in unconsolidated joint ventures.

[8] Corporate & Other represents all corporate-level items (including interest and other investment income, interest expense and non-property general and administrative expense) as well as intercompany eliminations necessary to reconcile to consolidated Company totals.