Subsequent Events (Details) - USD ($) $ in Thousands	Oct. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Subsequent Events [Line Items]
Unsecured debt		$ 845,223	$ 844,159
Subsequent Event | Joint Venture
Subsequent Events [Line Items]
Subsequent Event, Description	Vornado’s Board of Trustees approved the tax-free spin-off of our Washington, DC business and we entered into a definitive agreement to merge it with the business and certain select assets of The JBG Companies (“JBG”), a Washington, DC real estate company
Subsequent Event | Joint Venture | Pro Rata Distribution
Subsequent Events [Line Items]
Initial Form 10 registration statement relating to the spin-off is expected to be filed with the SEC	Fourth quarter of 2016
Distribution and combination are expected to be completed	Second quarter of 2017
Subsequent Event | Joint Venture | Vornado Realty Trust and Vornado Realty LP | Pro Rata Distribution
Subsequent Events [Line Items]
Pro rata basis of distribution	1:2