Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
ASSETS
Operating (including $281,602 and $265,138 of consolidated variable interest entities, respectively)	$ 4,815,667	$ 4,618,258
Construction-in-progress	572,986	531,205
Real Estate Investment Property, At Cost, Total	5,388,653	5,149,463
Less accumulated depreciation and amortization (including $20,974 and $19,086 of consolidated variable interest entities, respectively)	(1,383,520)	(1,350,471)
Net real estate	4,005,133	3,798,992
Cash and cash equivalents	75,699	88,927
Accounts and notes receivable, net	92,769	84,838
Mortgage notes receivable, net	55,287	55,155
Investment in real estate partnership	32,140	32,264
Prepaid expenses and other assets	130,921	145,062
Debt issuance costs, net of accumulated amortization of $10,261 and $9,535, respectively	13,698	14,056
TOTAL ASSETS	4,405,647	4,219,294
Liabilities
Mortgages payable (including $209,742 and $202,782 of consolidated variable interest entities, respectively)	658,264	588,456
Capital lease obligations	71,665	71,671
Notes Payable	300,910	300,822
Senior notes and debentures	1,361,098	1,360,913
Accounts payable and accrued expenses	157,357	156,270
Dividends payable	53,310	52,385
Security deposits payable	13,122	12,772
Other liabilities and deferred credits	105,285	100,283
Total liabilities	2,721,011	2,643,572
Commitments and contingencies (Note 7)
Redeemable noncontrolling interests	110,368	104,425
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, 67,267,030 and 66,701,422 shares issued and outstanding, respectively	673	667
Additional paid-in capital	2,114,666	2,062,708
Accumulated dividends in excess of net income	(637,638)	(623,795)
Accumulated other comprehensive loss	(1,960)	(1,417)
Total shareholders' equity of the Trust	1,485,738	1,448,160
Noncontrolling interests	88,530	23,137
Total shareholders' equity	1,574,268	1,471,297
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 4,405,647	$ 4,219,294