Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
CASH FLOWS FROM OPERATING ACTIVITIES:
Net (Loss) Income	$ (8,962)	$ (221,507)	$ 4,327
Adjustments to Reconcile Net (Loss) Income to Net Cash Provided by Operating Activities:
Depreciation	85,849	92,290	100,145
Amortization of Deferred Financing Costs	3,785	3,342	3,006
Other Amortization	33,218	37,320	48,804
Impairment of Real Estate, Net	(2,079)	186,160	6,934
Provision for Bad Debt	1,146	1,787	3,178
Equity in (Income) Loss of Joint Ventures	(980)	(675)	6,470
Distributions from Joint Ventures	1,033	3,032	2,319
Gain on Sale of Real Estate	(20,184)	(11,388)	(21,327)
Gain on Sale of Joint Venture Interests		(11,226)
Gain on Change in Control of Interests	(689)
Loss (Gain) on Retirement of Debt	5,299	4,304	(34,562)
Prepayment Premiums Associated with Retirement of Debt	(1,194)
Mark-to-Market Loss (Gain) on Interest Rate Protection Agreements	1,718	1,107	(3,667)
Equity in Income of Other Real Estate Partnerships	(11,891)	(3,494)	(18,516)
Distributions from Investment in Other Real Estate Partnerships	11,891	3,494	18,516
Decrease in Developments for Sale Costs			812
(Increase) Decrease in Tenant Accounts Receivable, Prepaid Expenses and Other Assets, Net	(3,154)	(1,526)	51,559
Increase in Deferred Rent Receivable	(7,275)	(6,300)	(7,104)
Decrease in Accounts Payable, Accrued Expenses, Other Liabilities, Rents Received in Advance and Security Deposits	(12,201)	(21,523)	(18,709)
Decrease (Increase) in Restricted Cash	105	(15)	7
Payments of Premiums and Discounts Associated with Senior Unsecured Notes	(5,260)	(6,840)	(2,576)
Net Cash Provided by Operating Activities	70,175	48,342	139,616
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of and Additions to Investment in Real Estate and Lease Costs	(82,896)	(85,757)	(68,855)
Net Proceeds from Sales of Investments in Real Estate	71,083	64,256	65,689
Investments in and Advances to Other Real Estate Partnerships	(125,089)	(149,773)	(105,095)
Distributions from Other Real Estate Partnerships in Excess of Equity in Income	191,178	205,038	140,073
Contributions to and Investments in Joint Ventures	(155)	(777)	(3,742)
Distributions and Sales Proceeds from Joint Venture Interests	650	11,519	6,333
Repayment of Notes Receivable	10,393	1,460	3,151
Increase in Lender Escrows	(97)	(435)
Net Cash Provided by Investing Activities	65,067	45,531	37,554
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt and Equity Issuance Costs	(6,502)	(4,228)	(7,624)
Unit Contributions	202,845	50,087	84,465
Unit Distributions			(12,614)
Repurchase and Retirement of Restricted Units	(1,001)	(298)	(739)
Preferred Unit Distributions	(15,254)	(19,677)	(20,296)
Repayments on Mortgage and Other Loans Payable	(67,164)	(20,393)	(13,462)
Proceeds from Origination of Mortgage Loans Payable	199,884	82,495	307,567
Settlement of Interest Rate Protection Agreements			(7,491)
Payments on Interest Rate Swap Agreement	(489)	(450)	(320)
Repayments on Senior Unsecured Notes	(234,307)	(259,018)	(336,196)
Proceeds from Unsecured Credit Facility	390,500	69,097	180,000
Repayments on Unsecured Credit Facility	(618,553)	(149,280)	(172,000)
Repurchase of Equity Component Exchangeable Notes			(33)
Costs Associated with the Retirement of Debt		(1,008)
Net Cash (Used in) Provided by Financing Activities	(150,041)	(252,673)	1,257
Net Effect of Exchange Rate Changes on Cash and Cash Equivalents	(61)	137	76
Net (Decrease) Increase in Cash and Cash Equivalents	(14,799)	(158,800)	178,427
Cash and Cash Equivalents, Beginning of Period	22,484	181,147	2,644
Cash and Cash Equivalents, End of Period	$ 7,624	$ 22,484	$ 181,147