Dispositions, Assets Held for Sale and Discontinued Operations (Details 2) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues:
Rental income, disposed	$ 5,495,000	$ 12,076,000	$ 28,121,000	$ 35,995,000
Expenses:
Interest expense, disposed	217,000	1,853,000	5,322,000	4,143,000
Property operating expenses, disposed	39,000	673,000	1,243,000	1,753,000
Depreciation expense, disposed	1,335,000	3,238,000	7,404,000	9,717,000
Expenses, disposed	1,591,000	5,764,000	13,969,000	15,613,000
Income (loss) from disposed properties	$ 3,904,000	$ 6,312,000	$ 14,152,000	$ 20,382,000