Segment Reporting Segment Reporting (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting [Abstract]
Rental income from real estate assets sold or held for sale, not classified as discontinued operations	$ 17,973	$ 44,645	$ 50,638
Operating expenses real estate assets sold or held for sale, not classified as discontinued operations	(7,053)	(17,288)	(19,250)
Net operating income from real estate assets sold or held for sale, not classified as discontinued operations	$ 10,920	$ 27,357	$ 31,388