Fair Value Measurements (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Liabilities [Abstract]
Mortgages payable	$ 1,061,953,000	$ 1,065,916,000
Marketable securities	34,460,000	31,206,000
Carrying Reported Amount Fair Value Disclosure [Member]
Assets [Abstract]
Cash Equivalents	328,678,000	289,054,000
Liabilities [Abstract]
Mortgages payable	1,061,953,000	1,065,916,000
Leasing commissions (included in Amounts due to Vornado)	45,189,000	45,803,000
Liabilities Not Measured At Fair Value	1,107,142,000	1,111,719,000
Estimate Of Fair Value Fair Value Disclosure [Member]
Assets [Abstract]
Cash Equivalents	328,678,000	289,054,000
Liabilities [Abstract]
Mortgages payable	1,106,000,000	1,097,000,000
Leasing commissions (included in Amounts due to Vornado)	45,000,000	46,000,000
Liabilities Not Measured At Fair Value	1,151,000,000	1,143,000,000
Fair Value, Inputs, Level 1 [Member]
Liabilities [Abstract]
Marketable securities	34,460,000	31,206,000
Fair Value, Inputs, Level 2 [Member]
Liabilities [Abstract]
Marketable securities	0	0
Fair Value, Inputs, Level 3 [Member]
Liabilities [Abstract]
Marketable securities	$ 0	$ 0

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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- Definition

Receivables to be collected from (obligations owed to) related parties, net as of the balance sheet date where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

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