Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
ASSETS
Accounts receivable, allowance for doubtful accounts	$ 37,674	$ 43,241
Receivable arising from the straight-lining of rents, allowance	3,165	3,290
Deferred leasing and financing costs, accumulated amortization	225,163	237,730
Identified intangible assets (included in other assets): Accumulated amortization	$ 356,379	$ 343,318
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Preferred shares of beneficial interest: authorized shares	110,000,000	110,000,000
Preferred shares of beneficial interest: issued shares	51,184,609	42,186,709
Preferred shares of beneficial interest: outstanding shares	51,184,609	42,186,709
Common shares of beneficial interest: par value per share	$ 0.04	$ 0.04
Common shares of beneficial interest: authorized shares	250,000,000	250,000,000
Common shares of beneficial interest: issued shares	186,734,711	185,080,020
Common shares of beneficial interest: outstanding shares	186,734,711	185,080,020
Common Class A [Member]
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Outstanding Partnership Units held by Third Parties	11,215,682	12,160,771
Cumulative Redeemable Preferred Unit [Member]
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Outstanding Partnership Units held by Third Parties	1,800,001	9,000,001