Quarterly report pursuant to Section 13 or 15(d)

Mortgages, Loans Payable And Other Obligations (Narrative) (Details)

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Mortgages, Loans Payable And Other Obligations (Narrative) (Details)
 3 Months Ended
Mar. 31, 2018
USD ($)
property
Mar. 31, 2017
USD ($)
Dec. 31, 2017
USD ($)
Debt Instrument [Line Items]      
Number of properties with encumbered company mortgages | property 9    
Carrying value of encumbered properties $ 1,300,000,000    
Cash paid for interest 19,103,000 $ 15,180,000  
Interest capitalized 7,109,000 4,997,000  
Total indebtedness $ 2,630,614,000   $ 2,826,110,000
Total indebtedness, weighted average interest rate 3.71%   3.93%
Projects Under Development And Developable Land [Member]      
Debt Instrument [Line Items]      
Number of properties with encumbered company mortgages | property 5    
Other Property [Member]      
Debt Instrument [Line Items]      
Carrying value of encumbered properties $ 487,000,000    
Unconsolidated Joint Venture [Member]      
Debt Instrument [Line Items]      
Interest capitalized 166,000 $ 1,009,000  
Revolving Credit Facility Borrowing And Other Variable Rate Mortgage Debt [Member]      
Debt Instrument [Line Items]      
Total indebtedness $ 464,183,000   $ 382,443,000
Total indebtedness, weighted average interest rate 3.94%   3.63%
Fixed Rate Debt And Other Obligations [Member]      
Debt Instrument [Line Items]      
Total indebtedness $ 2,166,431,000   $ 2,443,667,000
Total indebtedness, weighted average interest rate 3.66%   3.98%