Redeemable Noncontrolling Interests / Redeemable Partnership Units (Activity of Redeemable Noncontrolling Interests) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Redeemable Noncontrolling Interests Rollforward
Redeemable Noncontrolling Interest, Beginning Balance	$ 1,278,446	$ 1,229,221
Net income	10,910	53,654	$ 43,231
Other comprehensive income	643	4,699
Distributions	(33,229)	(31,342)
Other, net	35,408	32,473
Redeemable Noncontrolling Interest, Ending Balance	984,937	1,278,446	$ 1,229,221
Class A
Redeemable Noncontrolling Interests Rollforward
Redemption of Class A units for Vornado common shares, at redemption value	(38,747)	(36,510)
Adjustments to carry redeemable Class A units at redemption value	(268,494)	$ 26,251
JBGS \| Class A
Redeemable Noncontrolling Interests Rollforward
Adjustments to carry redeemable Class A units at redemption value	$ 224,069

Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders.

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- Definition

Decrease in noncontrolling interest (for example, but not limited to, redeeming or purchasing the interests of noncontrolling shareholders, issuance of shares (interests) by the non-wholly owned subsidiary to the parent entity for other than cash, and a buyback of shares (interest) by the non-wholly owned subsidiary from the noncontrolling interests).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4569655-111683

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4616395-111683

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- Definition

Amount of Net Income (Loss) attributable to redeemable noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.19)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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- Definition

As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 3A
-Subparagraph (12)(c)
-URI http://asc.fasb.org/extlink&oid=65877616&loc=SL6540498-122764

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
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-URI http://asc.fasb.org/extlink&oid=65877616&loc=SL6540498-122764

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=65877616&loc=SL6540498-122764

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- Definition

Adjustments to reflect redeemable Class A Operating Partnership units

+ References

No definition available.

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- Definition

Other Comprehensive Income, Net of Tax, Portion Attributable to Noncontrolling Interest

+ References

No definition available.

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- Definition

Other Net Attributable To Redeemable Noncontrolling Interest

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