Basis of Presentation and Significant Accounting Policies (Estimated Taxable Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Net income attributable to Vornado common shareholders	$ 27,319	$ (29,026)	$ 115,972	$ 47,752	$ 651,181	$ 66,125	$ 220,463	$ (114,163)	$ 162,017	$ 823,606	$ 679,856
Depreciation and amortization									213,083	302,092	227,297
Impairment losses									49,062	170,332	20,281
Straight-line rent adjustments									(36,696)	(137,941)	(144,727)
Tax expense related to the reduction of the value of our taxable REIT subsidiaries' deferred tax assets									32,663	0	(84,862)
Sale of real estate and other capital transactions									11,991	(39,109)	320,326
Vornado stock options									(6,383)	(3,593)	(8,278)
Earnings of partially owned entities									(3,054)	(149,094)	(5,299)
Net gain on extinguishment of Skyline properties debt									0	(457,970)	0
Tangible property regulations									0	0	(575,618)
Other, net									25,057	9,121	58,748
Estimated taxable income									$ 447,740	$ 517,444	$ 487,724