Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended		3 Months Ended						12 Months Ended
	Jan. 11, 2018	Jan. 04, 2018	Sep. 01, 2016	Jan. 31, 2018	Dec. 31, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock Number Of Shares Par Value And Other Disclosures
Common shares of beneficial interest: outstanding shares					189,983,858	189,983,858				189,100,876		189,983,858	189,100,876
Dividends paid on common shares												$ 496,490	$ 475,961	$ 474,751
Dividends per common share						$ 0.60	$ 0.60	$ 0.71	$ 0.71
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Proceeds from issuance of preferred shares / units												309,609	0	0
Preferred share / unit issuance cost (Series J redemption)												$ 0	$ (7,408)	0
Class A
Common Stock Number Of Shares Par Value And Other Disclosures
Outstanding Partnership Units held by Third Parties					12,528,899	12,528,899				12,197,162		12,528,899	12,197,162
Redeemable Series J
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred stock dividend rate			6.875%
Preferred stock, redemption amount			$ 246,250
Preferred share / unit issuance cost (Series J redemption)												$ (7,408)
Series I
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred share / unit issuance cost (Series J redemption)												(14,486)
Vornado Realty L.P.
Common Stock Number Of Shares Par Value And Other Disclosures
Dividends paid on common shares												$ 496,490	$ 475,961	474,751
Outstanding Partnership Units held by Third Parties					12,528,899	12,528,899						12,528,899
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Proceeds from issuance of preferred shares / units												$ 309,609	0	0
Preferred share / unit issuance cost (Series J redemption)												$ 0	$ (7,408)	$ 0
Vornado Realty L.P. | Class A
Common Stock Number Of Shares Par Value And Other Disclosures
Common shares of beneficial interest: outstanding shares					189,983,858	189,983,858						189,983,858
Dividends per common share						$ 0.60	0.60	$ 0.71	$ 0.71
Outstanding Partnership Units held by Third Parties					12,528,899	12,528,899				12,197,162		12,528,899	12,197,162
Redeemable Preferred Stock | Redeemable Series M
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred stock dividend rate					5.25%							5.25%
Preferred stock, redemption price per share					$ 25.00	$ 25.00						$ 25.00
Proceeds from issuance of preferred shares / units					$ 309,609
Sale of stock					12,780,000
Length of time to redeem shares from date of issuance					5 years
Redeemable Preferred Stock | Series G
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred stock dividend rate												6.625%
Redeemable Preferred Stock | Series I
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred stock dividend rate												6.625%
Subsequent Event | Series G
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred stock, redemption price per share		$ 25.00
Preferred stock, redemption amount		$ 200,000
Redemption of preferred shares, Shares / Units	4,800,000	6,000,000
Subsequent Event | Series I
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred stock, redemption price per share				$ 25.00
Preferred stock, redemption amount				$ 270,000
Subsequent Event | Redeemable Preferred Stock | Series G
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred stock dividend rate		6.625%
Subsequent Event | Redeemable Preferred Stock | Series I
Preferred Stock, Number of Shares, Par Value and Other Disclosures
Preferred stock dividend rate				6.625%
JBGS
Common Stock Number Of Shares Par Value And Other Disclosures
Dividends per common share						$ 0.1125	$ 0.1125			$ 0.1125
Pro rata basis of distribution												50%
JBGS | Vornado Realty L.P.
Common Stock Number Of Shares Par Value And Other Disclosures
Dividends per common share											$ 0.1125
Pro rata basis of distribution													0.5