Real Estate Fund Investments (Narrative) (Details)				3 Months Ended		12 Months Ended
	Feb. 16, 2018 USD ($)	Jan. 17, 2018 USD ($)	Mar. 01, 2011 USD ($)	Mar. 31, 2018 USD ($) investment	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) investment
Investment Holdings
Gain (loss) on sale of properties				$ 0	$ 2,267,000
(Loss) income from real estate fund investments				(8,807,000)	268,000
(Loss) income from partially owned entities				(9,904,000)	1,358,000
Number of investments held by fund | investment						5
Aggregate fair value of Real Estate Fund investments (in US Dollars)				$ 336,552,000		$ 354,804,000
Vornado Capital Partners Real Estate Fund
Investment Holdings
Equity method ownership percentage				25.00%
Term of the Fund, years				8 years
Investment period for commitments of the Fund, years				3 years
Investment fund expiration date				2013-07
Vornado Realty Trust
Investment Holdings
Unfunded commitments of fund				$ 33,513,000
Real estate fund investments
Investment Holdings
Real estate transfer tax				10,630,000	0
(Loss) income from real estate fund investments				$ (8,807,000)	$ 268,000
Number of investments held by fund | investment				4
Unfunded commitments of fund				$ 114,872,000
Eleven East 68th Street
Investment Holdings
Proceeds from sales of real estate and related investments		$ 82,000,000
Gain (loss) on sale of properties		$ 46,259,000
One Park Avenue
Investment Holdings
Payments to acquire real estate			$ 394,000,000
Real estate transfer tax			$ 3,000,000	$ 4,978,000
State and Local Jurisdiction | One Park Avenue
Investment Holdings
Additional real estate transfer tax	$ 9,491,000
Interest on real estate transfer tax	6,764,000
Real estate transfer tax and interest	15,608,000
(Loss) income from real estate fund investments	10,630,000
(Loss) income from partially owned entities	$ 4,978,000
Joint Venture | Vornado Capital Partners Real Estate Fund
Investment Holdings
Equity method ownership percentage			64.70%
Joint Venture | Crowne Plaza Times Square Hotel Joint Venture
Investment Holdings
Equity method ownership percentage				57.10%
Joint Venture | Crowne Plaza Times Square Hotel Joint Venture | Crowne Plaza Time Square Hotel
Investment Holdings
Ownership percentage by noncontrolling owners				24.70%
Joint Venture | Vornado Realty Trust
Investment Holdings
Equity method ownership percentage			30.30%
Joint Venture | Third Party
Investment Holdings
Equity method ownership percentage			5.00%