Related Party Transactions (Details) ft² in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2016 USD ($)	Mar. 31, 2017 USD ($) ft² $ / ft²	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Other Agreements
Property rentals		$ 38,273,000	$ 36,653,000
Rego Park II | Retail space | Toys R Us
Other Agreements
Area of property (in square feet) | ft²		47
Property rentals		$ 884,000	713,000
Bloomberg | Lease amendment
Other Agreements
Leasing commission	$ 8,916,000
Bloomberg | Lease amendment | Third party broker
Other Agreements
Leasing commission	7,200,000
Vornado
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		32.40%
Vornado | Toys R Us
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		32.50%
Vornado | 731 Lexington Avenue | Common Area
Management and Development Agreements
Property Management Fee Agreement Value (in US dollars)		$ 297,000
Vornado | Bloomberg | Lease amendment
Other Agreements
Leasing commission	$ 1,716,000
Vornado | Development fees
Management and Development Agreements
Development fee as percentage of development costs		6.00%
Other Agreements
Amount Due to / (Fees paid to) related party (in US dollars)		$ 52,000		$ 54,000
Vornado | Development fees | Alexander apartment tower
Other Agreements
Amount Due to / (Fees paid to) related party (in US dollars)			$ (5,784,000)
Vornado | Leasing Fees
Leasing Agreements
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%
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%
Other Agreements
Amount Due to / (Fees paid to) related party (in US dollars)		$ 1,000		415,000
Vornado | Property Management Fees
Management and Development Agreements
Management Fee Agreement Value (in US dollars)		$ 2,800,000
Vornado | Property Management Fees | 731 Lexington Avenue | Office And Retail Space
Management and Development Agreements
Property Management Fee Agreement Price Per Square Foot | $ / ft²		0.5
Vornado | Property Management Fees | 731 Lexington Avenue | Common Area
Management and Development Agreements
Property Management Fee Agreement Value (in US dollars)		$ 297,000
Property Management Fee Escalation Percentage Per Annum		3.00%
Vornado | Property Management Fees | Rego Park II | Retail space
Management and Development Agreements
Property Management Fee Agreement Percentage Of Income		2.00%
Vornado | Management, property management, cleaning and security fees
Other Agreements
Amount Due to / (Fees paid to) related party (in US dollars)		$ 489,000		$ 428,000