Earnings Per Share (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Aug. 18, 2011	Aug. 23, 2006
Numerator for net income per share - basic and diluted
Income (loss) from continuing operations	$ 17,389,000	$ (8,913,000)
Income (Loss) Attributable to Noncontrolling Interest	(582,000)	543,000
Partially Owned Properties	(450,000)	40,000
Preferred distributions	(3,466,000)	(3,466,000)
Income (Loss) from Continuing Operations Attributable to Parent	12,891,000	(11,796,000)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	128,942,000	135,661,000
Numerator for net income per share - basic and diluted	141,833,000	123,865,000
Income From Continuing Operations Available To Common Shares	13,473,000
Discontinued operations, net	134,778,000	141,979,000
Denominator for net income per share - basic and diluted	148,251,000	123,865,000
Weighted Average Number of Shares Outstanding, Basic	298,805	292,895
Dilutive Op Units	13,206
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options	3,219
Weighted average Common Shares outstanding	315,230	292,895
Net income per share - basic:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.043	$ (0.040)
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share	$ 0.432	$ 0.463
Net income available to Common Shares	$ 0.475	$ 0.423
Net income per share - diluted:
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.043	$ (0.040)
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$ 0.427	$ 0.463
Net income available to Common Shares	$ 0.470	$ 0.423
Earnings Per Share (Textuals) [Abstract]
Convertible Notes, outstanding			482,500,000	650,000,000
Partially Owned Properties	(450,000)	40,000
Dividend preference units	(3,466,000)	(3,466,000)
Income Loss From Continuing Operations Available To Units	13,473,000	(12,339,000)
Net Income loss available to Op unitholders basic diluted numerator	148,251,000	129,640,000
Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic	312,011	306,248
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options	3,219
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	315,230	306,248
OPERATING PARTNERSHIP
Numerator for net income per share - basic and diluted
Income (loss) from continuing operations	17,389,000	(8,913,000)
Partially Owned Properties	(450,000)	40,000
Discontinued operations, net	134,778,000	141,979,000
Earnings Per Share (Textuals) [Abstract]
Partially Owned Properties	$ (450,000)	$ 40,000
Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic	312,011	306,248
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	315,230	306,248
Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic	$ 0.475	$ 0.423
Net Income Loss Per Outstanding Limited Partnership And General Partnership Units Diluted	$ 0.470	$ 0.423
Income Losses From Continuing Operations Per Outstanding Limited Partnership And General Partnership Unit Basic	$ 0.043	$ (0.040)
Income (Loss) from Discontinued Operations, Net of Tax, Per Outstanding Limited Partnership and General Partnership Unit, Basic	$ 0.432	$ 0.463
Income Loss From Continuing Operations Per Outstanding Limited Partnership And General Partnership Units Diluted	$ 0.043	$ (0.040)
Income Loss From Discontinued Operations Net Of Tax Per Outstanding Limited Partnership And General Partnership nit Diluted	$ 0.427	$ 0.463