Earnings Per Share (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Aug. 18, 2011	Aug. 23, 2006
Numerator for net income per share - basic and diluted
Income from continuing operations	$ 36,558,000	$ 15,126,000	$ 52,759,000	$ 5,256,000
Income (Loss) Attributable to Noncontrolling Interest	(1,481,000)	(544,000)	(1,990,000)	43,000
Partially Owned Properties	(319,000)	(71,000)	(769,000)	(31,000)
Preferred distributions	(3,467,000)	(3,467,000)	(6,933,000)	(6,933,000)
Income (Loss) from Continuing Operations Attributable to Parent	31,291,000	11,044,000	43,067,000	(1,665,000)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	68,506,000	541,413,000	198,563,000	677,987,000
Numerator for net income per share - basic and diluted	99,797,000	552,457,000	241,630,000	676,322,000
Income From Continuing Operations Available To Common Shares	32,772,000	11,588,000	45,057,000
Discontinued operations, net	71,757,000	566,627,000	207,723,000	709,563,000
Net income per share - diluted	104,529,000	578,215,000	252,780,000	676,322,000
Weighted Average Number of Shares Outstanding, Basic	300,193	294,663	299,499	293,784
Dilutive Op Units	14,062	13,291	13,634
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options	3,393	4,245	3,324
Weighted average Common Shares outstanding	317,648	312,199	316,457	293,784
Net income per share - basic:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.104	$ 0.038	$ 0.144	$ (0.006)
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share	$ 0.228	$ 1.837	$ 0.663	$ 2.308
Net income available to Common Shares	$ 0.332	$ 1.875	$ 0.807	$ 2.302
Net income per share - diluted:
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.103	$ 0.037	$ 0.142	$ (0.006)
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$ 0.226	$ 1.815	$ 0.657	$ 2.308
Net income available to Common Shares	$ 0.329	$ 1.852	$ 0.799	$ 2.302
Earnings Per Share (Textuals) [Abstract]
Convertible Notes, outstanding					482,500,000	650,000,000
Dividend preference units	(3,467,000)	(3,467,000)	(6,933,000)	(6,933,000)
Income Loss From Continuing Operations Available To Units	32,772,000	11,588,000	45,057,000	(1,708,000)
Net Income loss available to Op unitholders basic diluted numerator	104,529,000	578,215,000	252,780,000	707,855,000
Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic	314,255	307,954	313,133	307,106
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options	3,393	4,245	3,324
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	317,648	312,199	316,457	307,106
OPERATING PARTNERSHIP
Numerator for net income per share - basic and diluted
Income from continuing operations	36,558,000	15,126,000	52,759,000	5,256,000
Partially Owned Properties	(319,000)	(71,000)	(769,000)	(31,000)
Discontinued operations, net	$ 71,757,000	$ 566,627,000	$ 207,723,000	$ 709,563,000
Earnings Per Share (Textuals) [Abstract]
Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic	314,255	307,954	313,133	307,106
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	317,648	312,199	316,457	307,106
Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic	$ 0.332	$ 1.875	$ 0.807	$ 2.302
Net Income Loss Per Outstanding Limited Partnership And General Partnership Units Diluted	$ 0.329	$ 1.852	$ 0.799	$ 2.302
Income Losses From Continuing Operations Per Outstanding Limited Partnership And General Partnership Unit Basic	$ 0.104	$ 0.038	$ 0.144	$ (0.006)
Income (Loss) from Discontinued Operations, Net of Tax, Per Outstanding Limited Partnership and General Partnership Unit, Basic	$ 0.228	$ 1.837	$ 0.663	$ 2.308
Income Loss From Continuing Operations Per Outstanding Limited Partnership And General Partnership Units Diluted	$ 0.103	$ 0.037	$ 0.142	$ (0.006)
Income Loss From Discontinued Operations Net Of Tax Per Outstanding Limited Partnership And General Partnership nit Diluted	$ 0.226	$ 1.815	$ 0.657	$ 2.308