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Mortgages Payable - Summary of Outstanding Mortgages Payable (Detail) - USD ($) $ in Thousands | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2020 | Dec. 31, 2019 | Dec. 12, 2018
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |
Notes payable | $ 1,117,879 | $ 970,961 |
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% |  |
Mortgages |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |
Mortgage payable gross | $ 1,120,544 | 974,836 |
Deferred debt issuance costs, net of accumulated amortization of $15,651 and $14,362, respectively | (2,665) | (3,875) |
Notes payable | 1,117,879 | 970,961 |
Deferred debt issuance costs, accumulated amortization | $ 15,651 | 14,362 |
Mortgages | 731 Lexington Avenue | Retail Space |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |
Maturity date | Aug. 01, 2020 |  |
Interest rate (in percentage) | 2.78% |  |
Mortgage payable gross | $ 350,000 | 350,000 |
Mortgages | 731 Lexington Avenue | Office Space |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |
Maturity date | Jun. 01, 2024 |  |
Interest rate (in percentage) | 1.61% |  |
Mortgage payable gross | $ 500,000 | 500,000 |
Mortgages | Paramus |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |
Maturity date | Oct. 01, 2021 |  |
Interest rate (in percentage) | 4.72% |  |
Mortgage payable gross | $ 68,000 | 68,000 |
Mortgages | Rego Park II | Retail Space |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |
Maturity date | Dec. 01, 2025 |  |
Interest rate (in percentage) | 2.29% |  |
Mortgage payable gross | $ 202,544 | $ 56,836 |
Notes payable |  |  | $ 252,544

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