Earnings Per Share (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Aug. 18, 2011	Aug. 23, 2006
Numerator for net income per share - basic and diluted
Income from continuing operations	$ 132,681,000	$ 30,217,000	$ 181,227,000	$ 33,721,000
Income (Loss) Attributable to Noncontrolling Interest	(5,750,000)	(1,142,000)	(7,477,000)	(1,018,000)
Partially Owned Properties	312,000	(387,000)	(457,000)	(418,000)
Preferred distributions	(2,386,000)	(3,466,000)	(9,319,000)	(10,399,000)
Redemption Premium	(5,150,000)	0	(5,150,000)	0
Income (Loss) from Continuing Operations Attributable to Parent	119,707,000	25,222,000	158,824,000	21,886,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	98,896,000	79,160,000	301,409,000	758,818,000
Numerator for net income per share - basic and diluted	218,603,000	104,382,000	460,233,000	780,704,000
Income From Continuing Operations Available To Common Shares	125,457,000	26,364,000	166,301,000	22,904,000
Discontinued operations, net	103,642,000	82,760,000	315,578,000	794,075,000
Net income per share - diluted	229,099,000	109,124,000	481,879,000	816,979,000
Weighted Average Number of Shares Outstanding, Basic	301,336	295,831	300,116	294,474
Dilutive Op Units	14,177	13,053	13,816	13,231
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options	3,260	3,960	3,333	4,203
Weighted average Common Shares outstanding	318,773	312,844	317,265	311,908
Net income per share - basic:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.397	$ 0.085	$ 0.529	$ 0.074
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share	$ 0.328	$ 0.268	$ 1.005	$ 2.577
Net income available to Common Shares	$ 0.725	$ 0.353	$ 1.534	$ 2.651
Net income per share - diluted:
Income (loss) from continuing operations available to Common Shares	$ 0.394	$ 0.084	$ 0.524	$ 0.073
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$ 0.325	$ 0.265	$ 0.995	$ 2.546
Net income available to Common Shares	$ 0.719	$ 0.349	$ 1.519	$ 2.619
Earnings Per Share (Textuals) [Abstract]
Convertible Notes, outstanding					482,500,000	650,000,000
Dividend preference units	(2,386,000)	(3,466,000)	(9,319,000)	(10,399,000)
Income Loss From Continuing Operations Available To Units	125,457,000	26,364,000	166,301,000	22,904,000
Net Income loss available to Op unitholders basic diluted numerator	229,099,000	109,124,000	481,879,000	816,979,000
Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic	315,513	308,884	313,932	307,705
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options	3,260	3,960	3,333	4,203
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	318,773	312,844	317,265	311,908
OPERATING PARTNERSHIP
Numerator for net income per share - basic and diluted
Income from continuing operations	132,681,000	30,217,000	181,227,000	33,721,000
Partially Owned Properties	312,000	(387,000)	(457,000)	(418,000)
Discontinued operations, net	$ 103,642,000	$ 82,760,000	$ 315,578,000	$ 794,075,000
Net income per share - basic:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.400	$ 0.090	$ 0.530	$ 0.070
Net income available to Common Shares	$ 0.730	$ 0.350	$ 1.530	$ 2.650
Net income per share - diluted:
Income (loss) from continuing operations available to Common Shares	$ 0.390	$ 0.080	$ 0.520	$ 0.070
Net income available to Common Shares	$ 0.720	$ 0.350	$ 1.520	$ 2.620
Earnings Per Share (Textuals) [Abstract]
Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic	315,513	308,884	313,932	307,705
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	318,773	312,844	317,265	311,908
Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic	$ 0.725	$ 0.353	$ 1.534	$ 2.651
Net Income Loss Per Outstanding Limited Partnership And General Partnership Units Diluted	$ 0.719	$ 0.349	$ 1.519	$ 2.619
Income Losses From Continuing Operations Per Outstanding Limited Partnership And General Partnership Unit Basic	$ 0.397	$ 0.085	$ 0.529	$ 0.074
Income (Loss) from Discontinued Operations, Net of Tax, Per Outstanding Limited Partnership and General Partnership Unit, Basic	$ 0.328	$ 0.268	$ 1.005	$ 2.577
Income Loss From Continuing Operations Per Outstanding Limited Partnership And General Partnership Units Diluted	$ 0.394	$ 0.084	$ 0.524	$ 0.073
Income Loss From Discontinued Operations Net Of Tax Per Outstanding Limited Partnership And General Partnership nit Diluted	$ 0.325	$ 0.265	$ 0.995	$ 2.546