Partners' Capital of the Operating Partnership - Additional Information (Details) - shares	9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Common Stock
Stockholders' Equity
Units outstanding (units)	64,398,000	64,387,000	64,380,000	64,316,000	64,302,000	64,105,000
SL Green Operating Partnership
Stockholders' Equity
Number of units of operating partnership owned by the noncontrolling interest unit holders (units)	4,139,334		3,670,343
SL Green Operating Partnership | Operating Partnership
Stockholders' Equity
Noncontrolling interest in the operating partnership (as a percent)	6.04%		5.39%
SL Green Operating Partnership | Common Stock
Stockholders' Equity
Units outstanding (units)	64,397,983
SL Green Operating Partnership | Series I Preferred Units
Stockholders' Equity
Units outstanding (units)	9,200,000
Period of restriction to redeem OP Units	1 year
Conversion of stock, shares issued	1