Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
ASSETS
Tenant and other receivables, allowance for doubtful accounts (in US dollars)	$ 11,908	$ 12,210
Receivable arising from the straight-lining of rents, allowance (in US dollars)	2,751	3,188
Deferred leasing costs, accumulated amortization (in US dollars)	218,239	212,339
Identified intangible assets, accumulated amortization (in US dollars)	$ 187,360	$ 199,821
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	52,676,629	52,678,939
Preferred shares of beneficial interest: outstanding shares	52,676,629	52,678,939
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	188,576,853	187,887,498
Common shares of beneficial interest: outstanding shares	188,576,853	187,887,498
Common Class A [Member]
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Outstanding Partnership Units held by Third Parties	12,242,820	11,356,550
Series D Cumulative Redeemable Preferred Unit [Member]
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Outstanding Partnership Units held by Third Parties	177,101	1