Dispositions, Assets Held for Sale and Discontinued Operations (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues:
Rental income, disposed	$ 19,990	$ 24,789	$ 38,552	$ 50,146
Expenses:
Interest expense, disposed	2,506	4,948	5,032	8,847
Property operating expenses, disposed	1,338	1,482	2,700	3,009
Depreciation expense, disposed	3,071	7,042	7,022	13,473
Expenses, disposed	6,915	13,472	14,754	25,329
Income (loss) from disposed properties	$ 13,075	$ 11,317	$ 23,798	$ 24,817