Quarterly report pursuant to Section 13 or 15(d)

Investments in Unconsolidated Real Estate Joint Ventures (Unconsolidated Real Estate Joint Ventures) (Details)

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Investments in Unconsolidated Real Estate Joint Ventures (Unconsolidated Real Estate Joint Ventures) (Details)
ft² in Thousands, $ in Thousands
 1 Months Ended 6 Months Ended
Jul. 31, 2017
USD ($)
Extension
Jun. 30, 2017
USD ($)
Sep. 30, 2017
USD ($)
ft²
Dec. 31, 2016
USD ($)
ft²
Columbus National Harbor RioCan Canada [Member]        
Schedule of Equity Method Investments [Line Items]        
Carrying Value of Investment     $ 125,800 $ 128,100
Columbus [Member]        
Schedule of Equity Method Investments [Line Items]        
Ownership %     50.00% 50.00%
Square Feet | ft²     355 355
Carrying Value of Investment     $ 6,800 $ 6,700
National Harbor [Member]        
Schedule of Equity Method Investments [Line Items]        
Ownership %     50.00% 50.00%
Square Feet | ft²     341 341
Carrying Value of Investment     $ 2,400 $ 4,100
RioCan Canda [Member]        
Schedule of Equity Method Investments [Line Items]        
Ownership %     50.00% 50.00%
Square Feet | ft²     924 901
Carrying Value of Investment     $ 116,600 $ 117,300
Charlotte and Galveston/Houston [Member]        
Schedule of Equity Method Investments [Line Items]        
Equity Method Investment Reported In Liabilities     $ (16,100) $ (6,300)
Charlotte [Member]        
Schedule of Equity Method Investments [Line Items]        
Ownership %     50.00% 50.00%
Square Feet | ft²     398 398
Equity Method Investment Reported In Liabilities     $ (3,600) $ (2,500)
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     $ (12,500) $ (3,800)
Unconsolidated Properties [Member]        
Schedule of Equity Method Investments [Line Items]        
Total joint venture debt, net     351,322 335,971
Unconsolidated Properties [Member] | Columbus [Member]        
Schedule of Equity Method Investments [Line Items]        
Total joint venture debt, net     84,400 84,200
Unconsolidated Properties [Member] | National Harbor [Member]        
Schedule of Equity Method Investments [Line Items]        
Total joint venture debt, net     86,400 86,100
Unconsolidated Properties [Member] | RioCan Canda [Member]        
Schedule of Equity Method Investments [Line Items]        
Total joint venture debt, net     11,400 11,100
Unconsolidated Properties [Member] | Charlotte [Member]        
Schedule of Equity Method Investments [Line Items]        
Total joint venture debt, net     89,800 89,700
Unconsolidated Properties [Member] | Galveston/Houston [Member]        
Schedule of Equity Method Investments [Line Items]        
Total joint venture debt, net     79,400 64,900
Mortgages [Member] | Unconsolidated Properties [Member]        
Schedule of Equity Method Investments [Line Items]        
Net discount and debt origination costs     $ (1,600) $ (1,600)
Mortgages [Member] | Unconsolidated Properties [Member] | Galveston/Houston [Member]        
Schedule of Equity Method Investments [Line Items]        
Principal $ 80,000 $ 70,000    
Number of mortgage extensions | Extension 2      
Term of mortgage extension 1 year      
Basis spread on variable rate 1.65% 1.50%    
Proceeds from Issuance of Debt $ 14,500