Discontinued Operations (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
REVENUES
Rental income									$ 96,156,000	$ 289,921,000	$ 376,310,000
Total revenues									96,156,000	289,921,000	376,310,000
EXPENSES
Property and maintenance									47,972,000	115,215,000	144,166,000
Real estate taxes and insurance									6,152,000	23,306,000	34,750,000
Depreciation									16,653,000	60,257,000	81,649,000
General and administrative									53,000	42,000	43,000
Total expenses									70,830,000	198,820,000	260,608,000
Discontinued operating income									25,326,000	91,101,000	115,702,000
Interest and other income									(184,000)	(800,000)	(127,000)
Other expenses									0	0	(11,000)
Interest:
Expense incurred, net									(203,000)	(10,070,000)	(11,654,000)
Amortization of deferred financing costs									(840,000)	(292,000)	(800,000)
Income and other tax (expense) benefit									243,000	(86,000)	1,073,000
Discontinued operations									24,710,000	81,453,000	104,437,000
Net gain on sales of discontinued operations									(826,489,000)	(297,956,000)	(335,299,000)
Discontinued operations, net	68,435,000	78,561,000	563,568,000	140,635,000	246,628,000	30,914,000	22,696,000	79,171,000	851,199,000	379,409,000	439,736,000
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net					656,722,106.38					656,722,106.38
Disposal Group Including Discontinued Operation Mortgage Notes Payable					$ 76,015,809.69					$ 76,015,809.69