Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
ASSETS
Operating (including $263,664 and $263,570 of consolidated variable interest entities, respectively)	$ 4,276,146	$ 4,232,608
Construction-in-progress	264,982	193,836
Real Estate Investment Property, At Cost, Total	4,541,128	4,426,444
Less accumulated depreciation and amortization (including $10,253 and $4,991 of consolidated variable interest entities, respectively)	(1,195,336)	(1,127,588)
Net real estate	3,345,792	3,298,856
Cash and cash equivalents	147,680	67,806
Accounts and notes receivable, net	82,152	75,921
Mortgage notes receivable, net	55,661	55,967
Investment in real estate partnership	33,871	34,352
Prepaid expenses and other assets	127,592	121,492
Debt issuance costs, net of accumulated amortization of $10,051 and $9,098, respectively	11,591	11,816
TOTAL ASSETS	3,804,339	3,666,210
Liabilities
Mortgages payable (including $205,907 and $207,683 of consolidated variable interest entities, respectively)	730,643	747,523
Capital lease obligations	71,698	63,093
Notes payable	299,618	295,159
Senior notes and debentures	1,076,456	1,004,635
Accounts payable and accrued expenses	121,233	104,660
Dividends payable	47,556	44,229
Security deposits payable	13,009	12,221
Other liabilities and deferred credits	50,353	68,761
Total liabilities	2,410,566	2,340,281
Commitments and contingencies (Note 7)
Redeemable noncontrolling interests	81,851	85,325
Shareholders' equity
Preferred shares, authorized 15,000,000 shares, $.01 par: 5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 399,896 shares issued and outstanding	9,997	9,997
Common shares of beneficial interest, $.01 par, 100,000,000 shares authorized, 64,620,923 and 63,544,150 shares issued and outstanding, respectively	647	636
Additional paid-in capital	1,867,494	1,764,940
Accumulated dividends in excess of net income	(577,214)	(555,541)
Accumulated other comprehensive loss	(13,227)	(3,940)
Total shareholders' equity of the Trust	1,287,697	1,216,092
Noncontrolling interests	24,225	24,512
Total shareholders' equity	1,311,922	1,240,604
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 3,804,339	$ 3,666,210