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Investments in Unconsolidated Joint Ventures - Additional Information (Details) $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Oct. 31, 2016 | Dec. 31, 2019 USD ($) ft² unit | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2019 USD ($) ft² unit | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Investments in unconsolidated joint ventures | $ |  | $ 2,912,842 |  |  |  | $ 3,019,020 |  |  |  | $ 2,912,842 | $ 3,019,020 |
Net equity investment in VIEs | $ |  | $ 145,900 |  |  |  | 808,300 |  |  |  | $ 145,900 | 808,300 |
Approximate Square Feet |  | 27,607,971 |  |  |  |  |  |  |  | 27,607,971 |  |
Purchase price and other fair value adjustment | $ |  | $ 0 | $ 3,799 | $ 67,631 | $ (2,041) | $ 0 | $ (3,057) | $ 11,149 | $ 49,293 | $ 69,389 | $ 57,385 | $ 0
21 East 66th Street | Three Retail and Two Residential Units |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 32.28% |  |  |  |  |  |  |  | 32.28% |  |
Number of Stores | unit |  | 3 |  |  |  |  |  |  |  | 3 |  |
Number of residential units | unit |  | 1 |  |  |  |  |  |  |  | 1 |  |
21 East 66th Street | Three Residential Units |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 16.14% |  |  |  |  |  |  |  | 16.14% |  |
Number of residential units | unit |  | 3 |  |  |  |  |  |  |  | 3 |  |
Stonehenge Portfolio |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold | 90.00% |  |  |  |  |  |  |  |  |  |  |
400 East 57th Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold | 51.00% |  |  |  |  |  |  |  |  |  |  |
1552 Broadway |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Approximate Square Feet |  | 13,045 |  |  |  |  |  |  |  | 13,045 |  |
Joint venture |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Investments in unconsolidated joint ventures | $ |  | $ 2,912,842 |  |  |  |  |  |  |  | $ 2,912,842 |  |
Equity method investments with negative book value | $ |  | $ 80,900 |  |  |  |  |  |  |  | $ 80,900 |  |
Joint venture | 100 Park Avenue |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 49.90% |  |  |  |  |  |  |  | 49.90% |  |
Economic Interest, percent |  | 49.90% |  |  |  |  |  |  |  | 49.90% |  |
Approximate Square Feet |  | 834,000 |  |  |  |  |  |  |  | 834,000 |  |
Joint venture | 717 Fifth Avenue |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 10.92% |  |  |  |  |  |  |  | 10.92% |  |
Economic Interest, percent |  | 10.92% |  |  |  |  |  |  |  | 10.92% |  |
Approximate Square Feet |  | 119,500 |  |  |  |  |  |  |  | 119,500 |  |
Joint venture | 800 Third Avenue |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 60.52% |  |  |  |  |  |  |  | 60.52% |  |
Economic Interest, percent |  | 60.52% |  |  |  |  |  |  |  | 60.52% |  |
Approximate Square Feet |  | 526,000 |  |  |  |  |  |  |  | 526,000 |  |
Joint venture | 919 Third Avenue |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 51.00% |  |  |  |  |  |  |  | 51.00% |  |
Economic Interest, percent |  | 51.00% |  |  |  |  |  |  |  | 51.00% |  |
Approximate Square Feet |  | 1,454,000 |  |  |  |  |  |  |  | 1,454,000 |  |
Joint venture | 11 West 34th Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 30.00% |  |  |  |  |  |  |  | 30.00% |  |
Economic Interest, percent |  | 30.00% |  |  |  |  |  |  |  | 30.00% |  |
Approximate Square Feet |  | 17,150 |  |  |  |  |  |  |  | 17,150 |  |
Joint venture | 280 Park Avenue |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 50.00% |  |  |  |  |  |  |  | 50.00% |  |
Economic Interest, percent |  | 50.00% |  |  |  |  |  |  |  | 50.00% |  |
Approximate Square Feet |  | 1,219,158 |  |  |  |  |  |  |  | 1,219,158 |  |
Joint venture | 1552 Broadway |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 50.00% |  |  |  |  |  |  |  | 50.00% |  |
Economic Interest, percent |  | 50.00% |  |  |  |  |  |  |  | 50.00% |  |
Approximate Square Feet |  | 57,718 |  |  |  |  |  |  |  | 57,718 |  |
Joint venture | 10 East 53rd Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 55.00% |  |  |  |  |  |  |  | 55.00% |  |
Economic Interest, percent |  | 55.00% |  |  |  |  |  |  |  | 55.00% |  |
Approximate Square Feet |  | 354,300 |  |  |  |  |  |  |  | 354,300 |  |
Joint venture | 21 East 66th Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 32.28% |  |  |  |  |  |  |  | 32.28% |  |
Economic Interest, percent |  | 32.28% |  |  |  |  |  |  |  | 32.28% |  |
Approximate Square Feet |  | 13,069 |  |  |  |  |  |  |  | 13,069 |  |
Joint venture | 650 Fifth Avenue |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 50.00% |  |  |  |  |  |  |  | 50.00% |  |
Economic Interest, percent |  | 50.00% |  |  |  |  |  |  |  | 50.00% |  |
Approximate Square Feet |  | 69,214 |  |  |  |  |  |  |  | 69,214 |  |
Joint venture | 121 Greene Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 50.00% |  |  |  |  |  |  |  | 50.00% |  |
Economic Interest, percent |  | 50.00% |  |  |  |  |  |  |  | 50.00% |  |
Approximate Square Feet |  | 7,131 |  |  |  |  |  |  |  | 7,131 |  |
Joint venture | 55 West 46th Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 25.00% |  |  |  |  |  |  |  | 25.00% |  |
Economic Interest, percent |  | 25.00% |  |  |  |  |  |  |  | 25.00% |  |
Approximate Square Feet |  | 347,000 |  |  |  |  |  |  |  | 347,000 |  |
Joint venture | Stonehenge Portfolio |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold | 10.00% |  |  |  |  |  |  |  |  |  |  |
Approximate Square Feet |  | 1,439,016 |  |  |  |  |  |  |  | 1,439,016 |  |
Joint venture | 605 West 42nd Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 20.00% |  |  |  |  |  |  |  | 20.00% |  |
Economic Interest, percent |  | 20.00% |  |  |  |  |  |  |  | 20.00% |  |
Approximate Square Feet |  | 927,358 |  |  |  |  |  |  |  | 927,358 |  |
Joint venture | 11 Madison Avenue |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 60.00% |  |  |  |  |  |  |  | 60.00% |  |
Economic Interest, percent |  | 60.00% |  |  |  |  |  |  |  | 60.00% |  |
Approximate Square Feet |  | 2,314,000 |  |  |  |  |  |  |  | 2,314,000 |  |
Joint venture | 333 East 22nd St |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 33.33% |  |  |  |  |  |  |  | 33.33% |  |
Economic Interest, percent |  | 33.33% |  |  |  |  |  |  |  | 33.33% |  |
Approximate Square Feet |  | 26,926 |  |  |  |  |  |  |  | 26,926 |  |
Joint venture | 400 East 57th Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 51.00% |  |  |  |  |  |  |  | 51.00% |  |
Economic Interest, percent |  | 41.00% |  |  |  |  |  |  |  | 41.00% |  |
Approximate Square Feet |  | 290,482 |  |  |  |  |  |  |  | 290,482 |  |
Joint venture | One Vanderbilt |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 71.01% |  |  |  |  |  |  |  | 71.01% |  |
Economic Interest, percent |  | 71.01% |  |  |  |  |  |  |  | 71.01% |  |
Approximate Square Feet |  | 0 |  |  |  |  |  |  |  | 0 |  |
Joint venture | Worldwide Plaza |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 24.35% |  |  |  |  |  |  |  | 24.35% |  |
Economic Interest, percent |  | 24.35% |  |  |  |  |  |  |  | 24.35% |  |
Approximate Square Feet |  | 2,048,725 |  |  |  |  |  |  |  | 2,048,725 |  |
Joint venture | 1515 Broadway |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 56.87% |  |  |  |  |  |  |  | 56.87% |  |
Economic Interest, percent |  | 56.87% |  |  |  |  |  |  |  | 56.87% |  |
Approximate Square Feet |  | 1,750,000 |  |  |  |  |  |  |  | 1,750,000 |  |
Joint venture | 2 Herald Square |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 51.00% |  |  |  |  |  |  |  | 51.00% |  |
Economic Interest, percent |  | 51.00% |  |  |  |  |  |  |  | 51.00% |  |
Approximate Square Feet |  | 369,000 |  |  |  |  |  |  |  | 369,000 |  |
Joint venture | Spring Street 115 |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership Interest Sold |  | 51.00% |  |  |  |  |  |  |  | 51.00% |  |
Economic Interest, percent |  | 51.00% |  |  |  |  |  |  |  | 51.00% |  |
Approximate Square Feet |  | 5,218 |  |  |  |  |  |  |  | 5,218 |  |
919 Third Avenue | Joint venture | 919 Third Avenue |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Purchase price and other fair value adjustment | $ |  |  |  |  |  |  |  |  |  | $ 49,300 |  |
400 East 57th Street |  |  |  |  |  |  |  |  |  |  |  |
General information on each joint venture |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage in disposed asset | 49.00% |  |  |  |  |  |  |  |  |  |  |

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