Dispositions, Assets Held for Sale and Discontinued Operations (Details 2) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues:
Rental income, disposed	$ 7,164,000	$ 26,123,000	$ 24,237,000	$ 89,593,000
Expenses:
Interest expense, disposed	1,041,000	4,507,000	3,991,000	18,512,000
Property operating expenses, disposed	1,577,000	1,595,000	4,586,000	6,017,000
Depreciation expense, disposed	123,000	7,878,000	4,760,000	27,106,000
Expenses, disposed	2,741,000	13,980,000	13,337,000	51,635,000
Income (loss) from disposed properties	$ 4,423,000	$ 12,143,000	$ 10,900,000	$ 37,958,000