CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
REVENUES
Rental income	$ 2,114,142,000	$ 1,874,465,000	$ 1,665,233,000
Fee and asset management	9,573,000	9,026,000	9,476,000
Total revenues	2,123,715,000	1,883,491,000	1,674,709,000
EXPENSES
Property and maintenance	415,986,000	387,968,000	374,135,000
Real estate taxes and insurance	241,876,000	211,518,000	200,779,000
Property management	81,902,000	81,867,000	79,857,000
Fee and asset management	4,663,000	4,279,000	4,998,000
Depreciation	664,082,000	612,579,000	581,469,000
General and administrative	47,248,000	43,605,000	39,881,000
Impairment	0	0	45,380,000
Total expenses	1,455,757,000	1,341,816,000	1,326,499,000
Operating income	667,958,000	541,675,000	348,210,000
Interest and other income	150,547,000	7,965,000	5,118,000
Other expenses	(27,361,000)	(14,292,000)	(11,792,000)
Interest:
Expense incurred, net	(457,666,000)	(464,277,000)	(460,748,000)
Amortization of deferred financing costs	(21,370,000)	(16,766,000)	(9,576,000)
Income (loss) before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	312,108,000	54,305,000	(128,788,000)
Income and other tax (expense) benefit	(539,000)	(728,000)	(291,000)
(Loss) from investments in unconsolidated entities	(14,000)	0	(735,000)
Net gain on sales of unconsolidated entities	0	0	28,101,000
Net (loss) gain on sales of land parcels	0	4,217,000	(1,395,000)
(Loss) income from continuing operations	311,555,000	57,794,000	(103,108,000)
Discontinued operations, net	569,649,000	877,403,000	399,091,000
Net income	881,204,000	935,197,000	295,983,000
Net (income) loss attributable to Noncontrolling Interests:
Operating Partnership	(38,641,000)	(40,780,000)	(13,099,000)
Net (income) loss attributable to Noncontrolling Interests - Partially Owned Properties	(844,000)	(832,000)	726,000
Net income attributable to controlling interests	841,719,000	893,585,000	283,610,000
Preferred distributions	(10,355,000)	(13,865,000)	(14,368,000)
Premium on redemption of Preferred Shares	(5,152,000)	0	0
Net income available to Common Shares	$ 826,212,000	$ 879,720,000	$ 269,242,000
Earnings per share - basic:
Income (loss) from continuing operations available to Common Shares	$ 0.932	$ 0.140	$ (0.393)
Net income available to Common Shares	$ 2.729	$ 2.984	$ 0.952
Weighted average Common Shares outstanding	302,701	294,856	282,888
Earnings per share - diluted:
Income (loss) from continuing operations available to Common Shares	$ 0.923	$ 0.138	$ (0.393)
Net income per share - diluted	$ 2.705	$ 2.950	$ 0.952
Weighted average Common Shares outstanding	319,766	312,065	282,888