Mortgages, Loans Payable And Other Obligations (Narrative) (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) property item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Debt Instrument [Line Items]
Cash paid for interest	$ 115,123,000	$ 119,664,000	$ 123,213,000
Interest capitalized	16,217,000	15,470,000	12,885,000
Total indebtedness	$ 2,154,920,000	$ 2,088,654,000
Total indebtedness, weighted average interest rate	5.22%	5.64%
Projects Under Development And Developable Land [Member]
Debt Instrument [Line Items]
Number of projects with encumbered company mortgages | item	4
Carrying value of encumbered properties	$ 215,000,000
Other Property [Member]
Debt Instrument [Line Items]
Number of properties with encumbered company mortgages | property	23
Carrying value of encumbered properties	$ 739,000,000
Revolving Credit Facility Borrowing And Other Variable Rate Mortgage Debt [Member]
Debt Instrument [Line Items]
Total indebtedness	$ 292,399,000	$ 159,860,000
Total indebtedness, weighted average interest rate	2.81%	3.83%
Fixed Rate Debt And Other Obligations [Member]
Debt Instrument [Line Items]
Total indebtedness	$ 1,862,521,000	$ 1,928,794,000
Total indebtedness, weighted average interest rate	5.60%	5.79%
Unconsolidated Joint Venture [Member]
Debt Instrument [Line Items]
Interest capitalized	$ 5,325,000	$ 4,646,000	$ 1,326,000