Commitments and Contingencies (Details) (USD $)			9 Months Ended			12 Months Ended	9 Months Ended	0 Months Ended		9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Lexington Avenue Property [Member]	Sep. 30, 2014 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]	Sep. 30, 2014 Flushing Property [Member]	Jun. 24, 2014 Rego Park I [Member] Sears Roebuck And Company [Member] Minimum [Member]	Jun. 24, 2014 Rego Park I [Member] Sears Roebuck And Company [Member] Minimum [Member] Estimated Future Damages [Member]	Sep. 30, 2014 General Liability [Member]	Sep. 30, 2014 All Risk Property And Rental Value [Member]	Sep. 30, 2014 Terrorism Coverage Including Nbcr [Member]	Sep. 30, 2014 NBCR [Member]
Insurance [Abstract]
Mortgage loans, recourse			$ 75,000,000
Mortgages payable	1,033,541,000	1,049,959,000	320,000,000	68,000,000
Insurance Maximum Coverage Per Incident										300,000,000	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%
Loss Contingency [Abstract]
Loss Contingency, Damages Sought, Value								4,000,000	25,000,000
Flushing Property [Abstract]
Non-refundable purchase deposit							1,875,000
Indemnification Sought by Tenant							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	1,033,541,000	1,049,959,000	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, net cash proceeds from sale of land						7,000,000
Purchase option excercised, gain on sale of land						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