Related Party Transactions (Details) ft² in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2016 USD ($) ft²	Mar. 31, 2016 USD ($) ft² $ / ft²	Mar. 31, 2015 USD ($)	Jan. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Rego Park II [Member] | Retail Space [Member] | Toys R Us [Member]
Other Agreements [Abstract]
Area of property (in square feet) | ft²	47	47
Rent related to leased space		$ 713,237
Leasing Fees [Member]
Summary of fees to Vornado
Fees owed (in US dollars)				$ 8,916,000
Vornado [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	32.40%	32.40%
Management and Development Agreements [Abstract]
Management Fee Agreement Value (in US dollars)		$ 2,800,000
Leasing Agreement [Abstract]
Asset Sale Commission Threshold (in US dollars)		$ 50,000,000
Percentage Commissions On Sale Of Assets Under Fifty Million		3.00%
Percentage Commissions On Sale Of Assets Over Fifty Million		1.00%
Summary of fees to Vornado
Fees to related party (in US dollars)		$ 8,317,000	$ 2,776,000
Vornado [Member] | Toys R Us [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	32.50%	32.50%
Vornado [Member] | 731 Lexington Avenue [Member] | Office And Retail Space [Member]
Management and Development Agreements [Abstract]
Property Management Fee Agreement Price Per Square Foot | $ / ft²		0.5
Vornado [Member] | 731 Lexington Avenue [Member] | Common Area [Member]
Management and Development Agreements [Abstract]
Property Management Fee Agreement Value (in US dollars)		$ 289,000
Property Management Fee Escalation Percentage Per Annum		3.00%
Vornado [Member] | Rego Park II [Member]
Management and Development Agreements [Abstract]
Property Management Fee Agreement Percentage Of Income		2.00%
Vornado [Member] | Alexander Apartment Tower [Member]
Summary of fees to Vornado
Development Fees Paid	$ 5,784,000
Vornado [Member] | Company Management Fees [Member]
Summary of fees to Vornado
Fees to related party (in US dollars)		$ 700,000	700,000
Vornado [Member] | Development fees [Member]
Management and Development Agreements [Abstract]
Development fee as percentage of development costs		6.00%
Summary of fees to Vornado
Fees to related party (in US dollars)		$ 44,000	764,000
Fees owed (in US dollars)	36,000	$ 36,000			$ 5,795,000
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)		$ 6,458,000	382,000
Fees owed (in US dollars)	4,000	4,000		$ 1,716,000	2,473,000
Vornado [Member] | Property Management Fees [Member]
Summary of fees to Vornado
Fees to related party (in US dollars)		1,115,000	$ 930,000
Fees owed (in US dollars)	$ 434,000	$ 434,000			$ 283,000