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Mortgages Payable (Details) (USD $) | Jun. 30, 2013 | Dec. 31, 2012
--- | --- | ---
Mortgage Loans on Real Estate [Line Items] |  |
Mortgage payable (in US Dollars) | $ 1,058,028,000 | $ 1,065,916,000
Rego Park 1 Shopping [Member] | Mortgages [Member] | Secured Debt [Member] |  |
Mortgage Loans on Real Estate [Line Items] |  |
Debt Instrument Maturity Date String | 2015-03 |
Interest rate | 0.40% |
Mortgage payable (in US Dollars) | 78,246,000 | 78,246,000
Percentage of cash mortgage collateralized | 100.00% |
Rego Park 2 Property [Member] | Mortgages [Member] | Secured Debt [Member] |  |
Mortgage Loans on Real Estate [Line Items] |  |
Debt Instrument Maturity Date String | 2018-11 |
Interest rate | 2.05% |
Mortgage payable (in US Dollars) | 270,896,000 | 272,245,000
Basis spread over LIBOR | 1.85% |
Lexington Avenue Property [Member] |  |
Mortgage Loans on Real Estate [Line Items] |  |
Mortgage payable (in US Dollars) | 320,000,000 |
Mortgage Loan Converted To Recourse (in US Dollars) | 75,000,000 |
Lexington Avenue Property [Member] | Mortgages [Member] | Secured Debt [Member] | Office Space [Member] |  |
Mortgage Loans on Real Estate [Line Items] |  |
Debt Instrument Maturity Date String | 2014-02 |
Interest rate | 5.33% |
Mortgage payable (in US Dollars) | 320,886,000 | 327,425,000
Lexington Avenue Property [Member] | Mortgages [Member] | Secured Debt [Member] | Retail Site [Member] |  |
Mortgage Loans on Real Estate [Line Items] |  |
Debt Instrument Maturity Date String | 2015-07 |
Interest rate | 4.93% |
Mortgage payable (in US Dollars) | 320,000,000 | 320,000,000
Lexington Avenue Property [Member] | Mortgages [Member] | Secured Debt [Member] | Retail Site [Member] | Maximum [Member] |  |
Mortgage Loans on Real Estate [Line Items] |  |
Mortgage Loan Converted To Recourse (in US Dollars) | 75,000,000 |
Paramus Property [Member] | Mortgages [Member] | Secured Debt [Member] |  |
Mortgage Loans on Real Estate [Line Items] |  |
Debt Instrument Maturity Date String | 2018-10 |
Interest rate | 2.90% |
Mortgage payable (in US Dollars) | $ 68,000,000 | $ 68,000,000

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- Definition Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 13, 16 -Article 9 + Details
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