Investments in Real Estate Partnerships - Schedule of Dispositions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) property	Dec. 31, 2016 USD ($) property
Unconsolidated Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Equity Method Investments | $	$ 27,144	$ 73,122	$ 174,090
Equity Method Investment, Realized Gain (Loss) on Disposal | $	16,624	34,276	70,907
Equity Method Investment, Realized Gain (Loss) on Disposal, Parent Company's Share | $	$ 3,608	$ 6,591	$ 25,003
Operating Segments [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Real Estate Properties Sold	10	6	11
Operating Segments [Member] | Unconsolidated Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Real Estate Properties Sold	1	3	10
Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Real Estate Properties Sold	9	9	16
Land [Member] | Unconsolidated Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Real Estate Properties Sold	2	1	1