Commitments and Contingencies (Details) (USD $)			12 Months Ended			12 Months Ended		1 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Lexington Avenue Property [Member]	Dec. 31, 2011 Kings Plaza Regional Shopping Center [Member]	Dec. 31, 2011 Paramus Property [Member]	Dec. 31, 2021 Paramus Property [Member] Tenant Occupant [Member] Ikea [Member]	Dec. 31, 2011 Paramus Property [Member] Tenant Occupant [Member] Ikea [Member] acre	Jun. 29, 2011 Flushing Property [Member]	Dec. 31, 2003 Flushing Property [Member]	Dec. 31, 2010 Flushing Property [Member]	Dec. 31, 2011 General Liability [Member]	Dec. 31, 2011 All Risk Property And Rental Value [Member]	Dec. 31, 2011 Terrorism Coverage Including Nbcr [Member] Self Insured [Member]	Dec. 31, 2011 Reinsurance For Terrorism Coverage Excluding Nbcr [Member] Third Party Carriers [Member]	Dec. 31, 2011 NBCR [Member]
Insurance [Abstract]
Mortgage loans, recourse			$ 75,000,000
Mortgage loan, carrying amount	1,330,932,000	1,246,411,000	320,000,000		68,000,000.00
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%
Environmental Remediation [Abstract]
Estimated total costs associated with clean up				2,500,000
Previously Paid Amounts For Environmental Liabilities				500,000
Flushing Property [Abstract]
Non-refundable purchase deposit, portion recognized as income									1,289,000
Non-refundable purchase deposit									1,875,000
Non-refundable purchase deposit, transaction costs									586,000
Litigation loss accrual										3,135,000
Payments for Legal Settlements								2,400,000
Gain (Loss) Related to Litigation Settlement								807,000
Litigation Loss Reserves Previously Accrued								3,207,000
Paramus Property [Abstract]
Acres Of Real Estate Land							30.3
Leases Of Lessor Rental Term Range							40 years
Property purchase option exercisable be leasee						75,000,000.00
Mortgage loan, carrying amount	1,330,932,000	1,246,411,000	320,000,000		68,000,000.00
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 excercised, gain on sale of land						62,000,000.00
Purchase Option Not Excercised 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	$ 4,998,000.00