Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
ASSETS
Tenant and other receivables, allowance for doubtful accounts (in US dollars)	$ 21,521	$ 21,869
Mortgage and mezzanine loans receivable, allowance (in US dollars)	5,811	5,845
Receivable arising from the straight-lining of rents, allowance (in US dollars)	3,375	4,355
Deferred leasing and financing costs, accumulated amortization (in US dollars)	286,668	264,451
Identified intangible assets, accumulated amortization (in US dollars)	$ 233,449	$ 277,998
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Preferred Stock, Par Value Per Share	$ 0		$ 0
Preferred shares of beneficial interest: authorized shares	110,000,000	110,000,000
Preferred shares of beneficial interest: issued shares	52,678,939	52,682,807
Preferred shares of beneficial interest: outstanding shares	52,678,939	52,682,807
Common shares of beneficial interest: par value per share (in dollars 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	187,664,768	187,284,688
Common shares of beneficial interest: outstanding shares	187,664,768	187,284,688
Common Class A [Member]
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Outstanding Partnership Units held by Third Parties	11,430,318	11,292,038
Cumulative Redeemable Preferred Unit [Member]
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Outstanding Partnership Units held by Third Parties	1	1