Commitments and Contingencies (Details) (USD $)					9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Lexington Avenue Property [Member]	Sep. 30, 2012 Kings Plaza Regional Shopping Center [Member]	Sep. 30, 2012 Paramus Property [Member] Tenant Occupant [Member] Ikea [Member] acre	Sep. 30, 2012 Flushing Property [Member]	Sep. 30, 2012 General Liability [Member]	Sep. 30, 2012 All Risk Property And Rental Value [Member]	Sep. 30, 2012 Terrorism Coverage Including Nbcr [Member] Self Insured [Member]	Sep. 30, 2012 Reinsurance For Terrorism Coverage Excluding Nbcr [Member] Third Party Carriers [Member]	Sep. 30, 2012 NBCR [Member]
Insurance [Abstract]
Insurance Maximum Coverage Per Incident							$ 300,000,000	$ 1,700,000,000	$ 1,700,000,000	$ 1,700,000,000
Deductible											275,000
Self Insured Responsibility											15.00%
Federal Government Responsibility											85.00%
Mortgage loans, recourse			75,000,000
Mortgage loan, carrying amount	1,069,776,000	1,080,932,000	320,000,000		68,000,000.00
Environmental Remediation [Abstract]
Estimated total costs associated with clean up				3,000,000
Previously Paid Amounts For Environmental Liabilities				500,000
Flushing Property [Abstract]
Non-refundable purchase deposit						1,875,000
Indemnification Sought by Tenant						50,000,000
Loss Contingency, Inestimable Loss						We believe, after consultation with counsel, that the amount or range of reasonably possible losses, if any, cannot be estimated
Paramus Property [Abstract]
Acres Of Real Estate Land					30.3
Leases Of Lessor Rental Term Range					40 years
Property purchase option exercisable by lessee					75,000,000.00
Fixed interest rate on the debt					2.90%
Triple-net rent, annual amount					700,000.00
Purchase option exercised, proceeds from sale of land					7,000,000.00
Purchase option exercised, gain on sale of land					62,000,000.00
Purchase option not exercised, amount included in triple net rent over remainder of lease					68,000,000.00
Loan Amortization Period					20 years
Letters Of Credit [Abstract]
Standby letters of credit, issued and outstanding	$ 3,998,000.00