Investments in Unconsolidated Real Estate Joint Ventures (Unconsolidated Real Estate Joint Ventures) (Details) ft² in Thousands, $ in Thousands	Jun. 30, 2020 USD ($) ft²	Dec. 31, 2019 USD ($) ft²
RioCan Canda [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet | ft²	765	764
Carrying Value of Investment	$ 92,100	$ 94,700
Columbus, Charlotte, National Harbor and Galveston/Houston [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment Reported In Liabilities	$ (44,800)	$ (42,100)
Columbus [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet | ft²	355	355
Equity Method Investment Reported In Liabilities	$ (3,900)	$ (3,500)
Charlotte [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet | ft²	399	399
Equity Method Investment Reported In Liabilities	$ (13,100)	$ (13,000)
National Harbor [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet | ft²	341	341
Equity Method Investment Reported In Liabilities	$ (7,800)	$ (5,900)
Galveston/Houston [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet | ft²	353	353
Equity Method Investment Reported In Liabilities	$ (20,000)	$ (19,700)
Unconsolidated Properties [Member]
Schedule of Equity Method Investments [Line Items]
Total joint venture debt, net	358,923	368,032
Unconsolidated Properties [Member] | RioCan Canda [Member]
Schedule of Equity Method Investments [Line Items]
Total joint venture debt, net	0	9,200
Unconsolidated Properties [Member] | Columbus [Member]
Schedule of Equity Method Investments [Line Items]
Total joint venture debt, net	85,000	85,000
Unconsolidated Properties [Member] | Charlotte [Member]
Schedule of Equity Method Investments [Line Items]
Total joint venture debt, net	99,600	99,500
Unconsolidated Properties [Member] | National Harbor [Member]
Schedule of Equity Method Investments [Line Items]
Total joint venture debt, net	94,500	94,400
Unconsolidated Properties [Member] | Galveston/Houston [Member]
Schedule of Equity Method Investments [Line Items]
Total joint venture debt, net	79,900	79,900
Mortgages [Member] | Unconsolidated Properties [Member]
Schedule of Equity Method Investments [Line Items]
Basis spread on variable rate	$ 1,100	$ 1,100