Interest and Other Investment Income, Net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Dividends and interest on marketable securities	$ 3,203us-gaap_InvestmentIncomeDividend	$ 3,106us-gaap_InvestmentIncomeDividend
Mark-to-market of investments in our deferred compensation plan	2,859	4,400
Interest on mezzanine loans receivable	1,674vno_InterestOnNotesReceivable	2,384vno_InterestOnNotesReceivable
Other, net	3,056us-gaap_OtherNonoperatingIncomeExpense	1,960us-gaap_OtherNonoperatingIncomeExpense
Interest and other investment (loss) income, net	$ 10,792	$ 11,850

The net amount of other income and expense amounts, the components of which are not separately disclosed on the income statement, resulting from ancillary business-related activities (that is, excluding major activities considered part of the normal operations of the business) also known as other nonoperating income (expense) recognized for the period. Such amounts may include: (a) dividends, (b) interest on securities, (c) net gains or losses on securities, (d) unusual costs, (e) gains or losses on foreign exchange transactions, and (f) miscellaneous other income and expense items.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 9

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.9)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Name:	us-gaap_OtherNonoperatingIncomeExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration