Noncontrolling Interests on the Company's Consolidated Financial Statements - Preferred Unit Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Rollforward Analysis of Preferred Unit Activity
Redemption of preferred units		$ (1,536)	$ (25,845)
SL Green Operating Partnership
Rollforward Analysis of Preferred Unit Activity
Redemption of preferred units		(1,536)	(25,845)
SL Green Operating Partnership | Preferred Units
Rollforward Analysis of Preferred Unit Activity
Balance at beginning of period	$ 202,169	283,285
Issuance of preferred units	0	0
Redemption of preferred units	(6,040)	(82,750)
Dividends paid on preferred units	(6,760)	(6,163)
Accrued dividends on preferred units	6,706	7,797
Balance at end of period	$ 196,075	$ 202,169	$ 283,285