Stockholders' Equity of the Company - Earnings per Share (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Basic Earnings:
Income (loss) attributable to SL Green common stockholders	$ 13,141	$ (39,731)
Less: distributed earnings allocated to participating securities	(434)	(406)
Net income (loss) attributable to SLGOP common unitholders (numerator for basic earnings per unit)	12,707	(40,137)
Effect of Dilutive Securities:
Add back: dilutive effect of earnings allocated to participating securities and contingently issuable shares	434	0
Add back: effect of dilutive securities (redemption of units to common shares)	901	(2,837)
Diluted Earnings:
Net (loss) income attributable to SL Green common stockholders, diluted	$ 14,042	$ (42,974)
Basic Shares:
Weighted average common shares outstanding (shares)	64,328,000	64,079,000
Effect of Dilutive Securities:
Operating Partnership units redeemable for common shares (shares)	4,439,000	4,103,000
Stock-based compensation plans (shares)	1,328,000	0
Diluted weighted average common stock outstanding (shares)	70,095,000	68,182,000
Common stock shares excluded from the diluted shares outstanding (shares)	135,000	1,275,225