Basis of Presentation and Significant Accounting Policies (Estimated Taxable Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Net income attributable to Vornado common shareholders / Class A unit holders	$ 193,217	$ 322,906	$ 2,400,195	$ 181,488	$ 100,494	$ 190,645	$ 111,534	$ (17,841)	$ 3,097,806	$ 384,832	$ 162,017
Sale of real estate and other capital transactions									(2,575,435)	31,527	11,991
Depreciation and amortization									200,913	234,325	213,083
Earnings of partially owned entities									150,550	15,711	(3,054)
Impairment losses									95,371	11,260	49,062
Tangible property regulations									(57,078)	(86,040)	0
Vornado stock options									(16,597)	(22,992)	(6,383)
Straight-line rent adjustments									9,057	(7,133)	(36,696)
Tax expense related to the reduction of our taxable REIT subsidiaries' deferred tax assets									0	0	32,663
Other, net									12,575	18,956	25,057
Estimated taxable income (unaudited)									$ 917,162	$ 580,446	$ 447,740