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Mortgages Payable - Additional Information (Detail) - USD ($) $ in Thousands | 9 Months Ended |
--- | --- | ---
Sep. 30, 2019 | Dec. 31, 2018
731 Lexington Avenue | Retail Site | Mortgages |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |
Debt instrument, description of variable rate basis | LIBOR |
731 Lexington Avenue | Retail Site | Mortgages | LIBOR |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |
Basis spread over LIBOR | 1.40% |
731 Lexington Avenue | Office Space | Mortgages |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |
Debt instrument, description of variable rate basis | LIBOR |
731 Lexington Avenue | Office Space | Mortgages | LIBOR |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |
Basis spread over LIBOR | 0.90% |
Rego Park II | Retail Site | Mortgages |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |
Debt instrument, description of variable rate basis | LIBOR |
Rego Park II | Retail Site | Mortgages | LIBOR |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |
Basis spread over LIBOR | 1.35% |
Participation Agreement | Rego Park II |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |
Loan participation balance | $ 195,708 | $ 195,708

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- Definition The aggregate amount of the participation liability at the end of the accounting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99377297&loc=d3e10013-112621 + Details
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