Organization and Basis of Presentation - Additional Information (Details)	3 Months Ended
	Mar. 31, 2023 USD ($) ft² building shares	Jun. 30, 2023 USD ($)	Dec. 31, 2022	Jul. 01, 2022 USD ($)	Jun. 30, 2022 USD ($)
Organization
Number of buildings | building	51
Area of office building (sqft) | ft²	29,708,910
Debt and preferred equity investments including investments held by unconsolidated joint ventures	$ 626,800,000
Debt and preferred equity investments and other financing receivables included in other balance sheet items	$ 8,500,000
Number of shares to be received on redemption of one unit of limited partnership interests (shares) | shares	1
625 Madison Avenue
Organization
Operating lease rent				$ 20,250,000	$ 4,610,000
625 Madison Avenue | Forecast
Organization
Carrying value of investment in leasehold interest		$ 0
Managed office properties
Organization
Number of buildings | building	1
Area of office building (sqft) | ft²	300,000
Service Corporation
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)	95.00%
Operating Partnership | SL Green Operating Partnership
Organization
Noncontrolling interest in the operating partnership (as a percent)	6.18%		5.39%
SL Green Management | SL Green Management LLC
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)	100.00%