Investments in Partially Owned Entities (Summary of Condensed Combined Financial Information) (Details) - Partially Owned Properties - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets	$ 13,384,000	$ 13,258,000
Liabilities	7,548,000	10,456,000
Noncontrolling interests	2,054,000	139,000
Equity	3,782,000	2,663,000
Total revenue	1,504	1,798	$ 12,991
Net income (loss)	$ 39	$ 52	$ (542)