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Mortgages Payable - Summary of Outstanding Mortgages Payable (Detail) - USD ($) $ in Thousands | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2020 | Sep. 14, 2020 | Sep. 13, 2020 | Dec. 31, 2019
Mortgage Loans on Real Estate |  |  |  |
Deferred debt issuance costs, net of accumulated amortization of $13,034 and $14,362 respectively | $ (8,374) |  |  |
Notes Payable (in US dollars) | 1,156,170 |  |  | $ 970,961
Mortgages |  |  |  |
Mortgage Loans on Real Estate |  |  |  |
Notes payable, gross | 1,164,544 |  |  | 974,836
Deferred debt issuance costs, net of accumulated amortization of $13,034 and $14,362 respectively | (8,374) |  |  | (3,875)
Notes Payable (in US dollars) | 1,156,170 |  |  | 970,961
Deferred debt issuance costs, accumulated amortization | $ 13,034 |  |  | 14,362
Mortgages | Paramus, NJ |  |  |  |
Mortgage Loans on Real Estate |  |  |  |
Maturity date | Oct. 04, 2021 |  |  |
Interest rate | 4.72% |  |  |
Notes payable, gross | $ 68,000 |  |  | 68,000
Mortgages | 731 Lexington Avenue | Retail space |  |  |  |
Mortgage Loans on Real Estate |  |  |  |
Maturity date | Aug. 05, 2025 |  |  |
Interest rate | 1.55% |  |  |
Notes payable, gross | $ 300,000 | $ 300,000 | $ 350,000 | 350,000
Mortgages | 731 Lexington Avenue | Office space |  |  |  |
Mortgage Loans on Real Estate |  |  |  |
Maturity date | Jun. 11, 2024 |  |  |
Interest rate | 1.06% |  |  |
Notes payable, gross | $ 500,000 |  |  | 500,000
Mortgages | Rego Park II | Retail space |  |  |  |
Mortgage Loans on Real Estate |  |  |  |
Maturity date | Dec. 12, 2025 |  |  |
Interest rate | 1.50% |  |  |
Notes payable, gross | $ 202,544 |  |  | 56,836
Mortgages | The Alexander apartment tower |  |  |  |
Mortgage Loans on Real Estate |  |  |  |
Maturity date | Nov. 01, 2027 |  |  |
Mortgages | The Alexander apartment tower | Retail space |  |  |  |
Mortgage Loans on Real Estate |  |  |  |
Interest rate | 2.63% |  |  |
Notes payable, gross | $ 94,000 |  |  | $ 0

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