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Mortgages Payable - Additional Information (Detail) $ in Thousands |  |  | 3 Months Ended |
--- | --- | --- | --- | ---
Feb. 14, 2020 USD ($) | Dec. 12, 2018 USD ($) | Mar. 31, 2020 USD ($) option | Dec. 31, 2019 USD ($)
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |
Mortgages payable, net of deferred debt issuance costs |  |  | $ 1,117,879 | $ 970,961
Mortgages |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |
Mortgages payable, net of deferred debt issuance costs |  |  | $ 1,117,879 | 970,961
731 Lexington Avenue | Retail Site | Mortgages |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |
Interest rate (in percentage) |  |  | 2.78% |
Maturity date |  |  | Aug. 01, 2020 |
Debt instrument, description of variable rate basis |  |  | LIBOR |
Number of renewal options | option |  |  | 2 |
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% |
Length of renewal term |  |  | 1 year |
731 Lexington Avenue | Office Space | Mortgages |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |
Interest rate (in percentage) |  |  | 1.61% |
Maturity date |  |  | Jun. 01, 2024 |
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 |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |
Interest rate (in percentage) |  |  | 2.29% |
Loan participation balance | $ 50,000 |  |  |
Proceeds from notes payable | $ 145,000 |  |  |
Rego Park II | Retail Site | Mortgages |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |
Mortgages payable, net of deferred debt issuance costs |  | $ 252,544 |  |
Interest rate (in percentage) |  |  | 2.29% |
Maturity date |  |  | Dec. 01, 2025 |
Loan participation balance |  |  |  | 195,708
Mortgages payable, net of loan participation |  |  | $ 202,544 | 56,836
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% | 1.35% |
Participation Agreement | Rego Park II | Retail Site | Mortgages |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |
Loan participation balance |  |  | $ 50,000 | $ 195,708

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