Segment Reporting (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting [Abstract]
Rental income from real estate assets sold or held for sale	$ 6,778	$ 15,138	$ 15,241	$ 33,198
Operating expenses from real estate assets sold or held for sale	(2,336)	(5,411)	(5,341)	(11,705)
Net operating income from real estate assets sold or held for sale	$ 4,442	$ 9,727	$ 9,900	$ 21,493