Related Party Transactions (Details) (USD $)	0 Months Ended	12 Months Ended
	Dec. 22, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Managment and Development Agreement [Abstract]
Property Management and Development Fee agreement		We pay Vornado an annual management fee equal to the sum of (i) $2,800,000, (ii) 2% of gross revenue from the Rego Park II shopping center, (iii) $0.50 per square foot of the tenant-occupied office and retail space at 731 Lexington Avenue, and (iv) $280,000, escalating at 3% per annum, for managing the common area of 731 Lexington Avenue. Vornado is also entitled to a development fee equal to 6% of development costs, as defined. The payment of development fees for the Rego Park II Apartment Tower is due on substantial completion of the construction, as defined.
Leasing Agreement [Abstract]
Leasing service fee payable, description		Vornado also provides us with leasing services for a fee of 3% of rent for the first ten years of a lease term, 2% of rent for the eleventh through the twentieth year of a lease term, and 1% of rent for the twenty-first through thirtieth year of a lease term, subject to the payment of rents by tenants. In the event third-party real estate brokers are used, the fees to Vornado increase by 1% and Vornado is responsible for the fees to the third-party real estate brokers.
Asset Sale Commission Threshold (in US dollars)		$ 50,000,000
Commission payable to Vornado incurred in connection with the sale of real estate		0	0	7,510,000
Kings Plaza Regional Shopping Center [Member]
Summary of fees to Vornado
Property management and leasing fees to Vornado related to Kings Plaza (in US dollars)				2,021,000
Mr. Roth, David Mandelbaum, and Russell B. Wight, Jr.
Related Party Transaction [Line Items]
Ownership Interest in the Company		26.30%
IP & Partners Through Vornado
Related Party Transaction [Line Items]
Ownership Interest in the Company		2.10%
Vornado [member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		32.40%
Managment and Development Agreement [Abstract]
Management Fee Agreement Value (in US dollars)		2,800,000
Leasing Agreement [Abstract]
Percentage Commissions On Sale Of Assets Under Fifty Million		3.00%
Percentage Commissions On Sale Of Assets Over Fifty Million		1.00%
Leasing services fee and commission on asset sale, annual installment, maximum. (in US dollars)	4,000,000
Debt Instrument, Description of Variable Rate Basis		LIBOR
Basis spread over LIBOR		1.00%
Repayment of leasing costs	40,353,000,000
Other Agreements [Abstract]
Other Supervisory Fees		6.00%
Summary of fees to Vornado
Fees to related party (in US dollars)		11,282,000	7,341,000	17,679,000
Vornado [member] | Lexington Avenue Property [Member] | Office And Retail Space [Member]
Managment and Development Agreement [Abstract]
Property Management Fee Agreement Price Per Square Foot		0.5
Vornado [member] | Lexington Avenue Property [Member] | Common Area [Member]
Managment and Development Agreement [Abstract]
Property Management Fee Agreement Value (in US dollars)		280,000
Property Management Fee Escalation Percentage Per Annum		3.00%
Vornado [member] | Rego Park 2 Property [Member]
Managment and Development Agreement [Abstract]
Property Management Fee Agreement Percentage Of Income		2.00%
Vornado [member] | Company Management Fees [Member]
Summary of fees to Vornado
Fees to related party (in US dollars)		2,800,000	2,800,000	2,983,000
Vornado [member] | Development fees [Member]
Managment and Development Agreement [Abstract]
Development fee as percentage of development costs		6.00%
Summary of fees to Vornado
Fees to related party (in US dollars)		3,394,000	0	438,000
Fees owed to Vornado (in US dollars)		3,394,000
Vornado [member] | Leasing Fees [Member]
Leasing Agreement [Abstract]
Lease Fee Percentage Of Rent One To Ten Years		3.00%
Lease Fee Percentage Of Rent Eleven To Twenty Years		2.00%
Lease Fee Percentage Of Rent Twenty First To Thirty Years		1.00%
Percentage Increase Lease Fee If Broker Used		1.00%
Summary of fees to Vornado
Fees to related party (in US dollars)		1,430,000	1,126,000	2,217,000
Fees owed to Vornado (in US dollars)		0
Vornado [member] | Commission On Sale Of Real Estate [Member]
Summary of fees to Vornado
Fees to related party (in US dollars)		0	0	7,510,000
Vornado [member] | Property Management Fees [Member]
Summary of fees to Vornado
Fees to related party (in US dollars)		3,658,000	3,415,000	4,531,000
Fees owed to Vornado (in US dollars)		$ 528,000