Dispositions, Assets Held for Sale and Discontinued Operations (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Rental income, disposed	$ 1,955	$ 31,966	$ 23,255	$ 99,057
Expenses:
Interest expense, disposed	0	4,939	1,714	16,697
Property operating expenses, disposed	2,111	1,476	7,209	4,411
Provision for depreciation, disposed	26	4,604	1,167	20,873
Expenses, disposed	2,137	11,019	10,090	41,981
Income (loss) from disposed properties	$ (182)	$ 20,947	$ 13,165	$ 57,076