Organization and Basis of Presentation - Narrative (Details) ft² in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2025 USD ($)	Dec. 31, 2024 USD ($) ft² building shares	Dec. 31, 2023
Organization
Number of shares to be received on redemption of one unit of limited partnership interests (shares) | shares		1
Subsequent Event | Mortgage To Finance Acquisition
Organization
Debt instrument, face amount	$ 80.0
Initial Term (in Years)	5 years
Interest rate added to base rate (as a percent)	2.40%
Interest rate, fixed rate debt (as a percent)	6.57%
Park Avenue 500 | Subsequent Event
Organization
Gross Asset Valuation (in millions)	$ 130.0
Managed Office Properties
Organization
Approximate square feet | ft²		0.4
Debt and preferred equity investments including investments held by unconsolidated joint ventures		$ 303.7
Debt and preferred equity investments and other financing receivables included in other balance sheet items		$ 9.7
Office
Organization
Number of Buildings | building		1
Retail building
Organization
Number of Buildings | building		1
Service Corporation
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)		95.00%
SLG Management LLC | SL Green Management
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)		100.00%
Operating Partnership | SL Green Operating Partnership
Organization
Noncontrolling interest in the operating partnership (as a percent)		5.97%	5.75%