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)
 9 Months Ended
Sep. 30, 2017
USD ($)
property
Sep. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Debt Instrument [Line Items]      
Number of properties with encumbered company mortgages | property 14    
Carrying value of encumbered properties $ 1,600,000,000    
Cash paid for interest 70,114,000 $ 89,617,000  
Interest capitalized 13,955,000 14,436,000  
Total indebtedness $ 2,856,676,000   $ 2,357,055,000
Total indebtedness, weighted average interest rate 3.87%   3.79%
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 $ 375,000,000    
Unconsolidated Joint Venture [Member]      
Debt Instrument [Line Items]      
Interest capitalized 1,009,000 $ 3,937,000  
Revolving Credit Facility Borrowing And Other Variable Rate Mortgage Debt [Member]      
Debt Instrument [Line Items]      
Total indebtedness $ 224,357,000   $ 481,282,000
Total indebtedness, weighted average interest rate 3.84%   2.93%
Fixed Rate Debt And Other Obligations [Member]      
Debt Instrument [Line Items]      
Total indebtedness $ 2,632,320,000   $ 1,875,773,000
Total indebtedness, weighted average interest rate 3.87%   4.01%