Segment Reporting Segment Reporting (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Rental income from real estate assets sold or held for sale	$ 88,865	$ 133,956	$ 179,226
Operating expenses from real estate assets sold or held for sale	(30,245)	(49,306)	(65,007)
Net operating income from real estate assets sold or held for sale	$ 58,620	$ 84,650	$ 114,219