Commitments and Contingencies (Details) (USD $)	12 Months Ended						12 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Lexington Avenue Property [Member]	Dec. 31, 2013 Paramus Property [Member] Tenant Occupant [Member] Ikea [Member]	Dec. 31, 2001 Paramus Property [Member] Tenant Occupant [Member] Ikea [Member] acre	Dec. 31, 2021 Paramus Property [Member] Tenant Occupant [Member] Ikea [Member] Scenario Forecast [Member]	Dec. 31, 2013 Paramus Property [Member] Tenant Occupant [Member] Ikea [Member] Scenario Forecast [Member]	Dec. 31, 2002 Flushing Property [Member]	Nov. 30, 2011 Flushing Property [Member] New World Mall Llc [Member]	Dec. 31, 2013 General Liability [Member]	Dec. 31, 2013 All Risk Property And Rental Value [Member]	Dec. 31, 2013 Terrorism Coverage Including Nbcr [Member] Self Insured [Member]	Dec. 31, 2013 Reinsurance For Terrorism Coverage Excluding Nbcr [Member] Third Party Carriers [Member]	Dec. 31, 2013 NBCR [Member]
Insurance [Abstract]
Mortgage loans, recourse				$ 75,000,000
Mortgages payable	1,049,959,000	1,065,916,000		320,000,000	68,000,000
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 (in percentage)															15.00%
Federal Government Responsibility (in percentage)															85.00%
Flushing Property [Abstract]
Non-refundable purchase deposit									1,875,000
Loss Contingency, Damages Sought, Value										50,000,000
Paramus Property [Abstract]
Area Of Land (in acre)						30.3
Property purchase option exercisable be leasee with purchase option in 2021								75,000,000
Mortgages payable	1,049,959,000	1,065,916,000		320,000,000	68,000,000
Fixed interest rate on the debt (in percentage)					2.90%
Triple-net rent, annual amount								700,000
Purchase option exercised, proceeds from sale of land								7,000,000
Purchase option excercised, gain on sale of land	0	599,628,000	0				60,000,000
Purchase option not excercised amount included in triple net rent over remainder of lease							68,000,000
Loan Amortization Period							20 years
Letters Of Credit [Abstract]
Standby letters of credit, issued and outstanding	$ 3,308,000