Organization and Basis of Presentation - Additional Information (Details) $ / shares in Units, $ in Millions					3 Months Ended
	Jan. 18, 2022 $ / shares shares	Jan. 10, 2022	Jan. 07, 2022 $ / shares	Dec. 02, 2021 $ / shares	Mar. 31, 2022 USD ($) ft² building $ / shares shares	Mar. 31, 2021 $ / shares	Apr. 30, 2022 USD ($)	Dec. 31, 2021
Organization
Cash distribution declared, per common share (in dollars per share)					$ 0.932	$ 0.938
Volume weighted average share price (in dollars per share)			$ 79.71
Number of buildings | building					58
Area of office building (sqft) | ft²					27,549,252
Debt and preferred equity investments including investments held by unconsolidated joint ventures | $					$ 1,100.0
Debt and preferred equity investments and other financing receivables included in other balance sheet items | $					$ 100.0
Number of shares to be received on redemption of one unit of limited partnership interests (shares) | shares					1
Shareholder Election, Cash Option Subject to Proration
Organization
Common stock, dividends, per share, cash paid (in dollars per share)	$ 0.3976
Common stock, dividends, per share, stock issued (in shares) | shares	0.0295
Shareholder Election, Stock Option
Organization
Common stock, dividends, per share, stock issued (in shares) | shares	0.0345
1080 Amsterdam Avenue
Organization
Sales price | $					$ 42.7
1080 Amsterdam Avenue | Subsequent Event
Organization
Sales price | $							$ 42.7
Stonehenge Properties | Subsequent Event
Organization
Sales price | $							$ 1.0
Managed office properties
Organization
Number of buildings | building					1
Area of office building (sqft) | ft²					300,000
Ordinary Dividend
Organization
Cash distribution declared, per common share (in dollars per share)				$ 0.3108
Special Dividend
Organization
Cash distribution declared, per common share (in dollars per share)				$ 2.4392
Common Stock
Organization
Reverse stock split conversion ratio		1.03060
SL Green Operating Partnership
Organization
Cash distribution declared, per common share (in dollars per share)					$ 0.932	$ 0.938
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)					6.00%			5.57%
SL Green Management | SL Green Management LLC
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)					100.00%