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Organization and Basis of Presentation - Additional Information (Details) - USD ($) |  | 6 Months Ended |
--- | --- | --- | ---
Aug. 07, 2018 | Jun. 30, 2018 | Dec. 31, 2017
SL Green Operating Partnership |  |  |
Organization |  |  |
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent) |  | 100.00% |
Noncontrolling interest in the operating partnership (as a percent) |  | 5.20% | 4.58%
Subsequent Event | Senior Unsecured Notes Due August 2021 | Senior Unsecured Notes |  |  |
Organization |  |  |
Face amount of loan | $ 350,000,000.0 |  |
Interest rate added to base rate (as a percent) | 0.98% |  |

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