Organization and Basis of Presentation - Additional Information (Details) $ in Thousands, ft² in Millions	1 Months Ended	6 Months Ended
	Jul. 31, 2025 USD ($)	Jun. 30, 2025 USD ($) ft² building shares	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Organization
Number of shares to be received on redemption of one unit of limited partnership interests (shares) | shares		1
Investments in unconsolidated joint ventures		$ 2,701,382		$ 2,690,138
Cash consideration		57,123	$ 325,282
Madison Avenue, 625, Transaction 1
Organization
Investments in unconsolidated joint ventures		$ 112,100
Madison Avenue, 625, Transaction 1 | Subsequent Event
Organization
Joint venture sold (as a percent)	0.500
Sale of preferred equity investment	$ 104,900
Madison Avenue, 625, Transaction 2 | Subsequent Event
Organization
Sale of preferred equity investment	10,900
Cash consideration	$ 23,700
Office Building
Organization
Number of buildings | building		1
Retail Site
Organization
Number of buildings | building		1
Managed Office Properties
Organization
Approximate square feet | ft²		0.4
Debt and preferred equity investments including investments held by unconsolidated joint ventures		$ 315,700
Debt and preferred equity investments and other financing receivables included in other balance sheet items		221,900
SL Green Operating Partnership
Organization
Investments in unconsolidated joint ventures		2,701,382		$ 2,690,138
Cash consideration		$ 57,123	$ 325,282
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)		6.40%		5.97%
SL Green Management | SL Green Management LLC
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)		100.00%