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Investments in Unconsolidated Joint Ventures - Acquisition, Development and Construction Arrangements/Sale of Joint Venture Interest or Property (Details) - USD ($) | 1 Months Ended | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Sep. 30, 2021 | Jun. 30, 2021 | Apr. 30, 2021 | Mar. 31, 2021 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Equity in net (loss) gain on sale of interest in unconsolidated joint venture/real estate |  |  |  |  | $ (1,280,000) | $ 0 | $ (5,438,000) | $ 0
55 West 46th Street, Tower 46 | Joint venture |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Ownership interest |  | 25.00% |  |  |  |  |  |
Gross Asset Valuation |  | $ 275,000.0 |  |  |  |  |  |
Equity in net (loss) gain on sale of interest in unconsolidated joint venture/real estate |  |  |  | $ (15,200) |  |  |  |
605 West 42nd Street | Joint venture |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Ownership interest | 20.00% |  |  |  | 20.00% |  | 20.00% |
Gross Asset Valuation | $ 858,100,000 |  |  |  | $ 858,100,000 |  | $ 858,100,000 |
Equity in net (loss) gain on sale of interest in unconsolidated joint venture/real estate |  | $ 8,900 |  |  |  |  |  |
East 400 Street 57 |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Asset impairment charges |  |  | $ 5,700,000 |  |  |  |  |
East 400 Street 57 | Joint venture |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Ownership interest | 41.00% |  |  |  | 41.00% |  | 41.00% |
Gross Asset Valuation | $ 133,500,000 |  |  |  | $ 133,500,000 |  | $ 133,500,000 |
Equity in net (loss) gain on sale of interest in unconsolidated joint venture/real estate | (1,000.0) |  |  |  |  |  |  |
Disposition Of Joint Venture Interests Or Properties In 2021 | Joint venture |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Employee-related liabilities | $ 1,400,000 |  |  |  | $ 1,400,000 |  | $ 1,400,000 |

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