Partners' Capital of the Operating Partnership - EPS (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Basic Loss:
Less: distributed earnings allocated to participating securities	$ (326)	$ (521)	$ (652)	$ (1,042)
Net loss attributable to SLGOP common unitholders (numerator for basic earnings per unit)	(26,829)	(11,613)	(111,546)	(33,209)
Add back: dilutive effect of earnings allocated to participating securities and contingently issuable shares	0	0	0	0
Loss attributable to SL Green common stockholders (numerator for diluted earnings per share)	(26,829)	(11,613)	(111,546)	(33,209)
SL Green Operating Partnership
Basic Loss:
Net loss attributable to SLGOP common unitholders	(28,658)	(11,867)	(119,727)	(34,407)
Less: distributed earnings allocated to participating securities	(860)	(1,243)	(1,721)	(2,486)
Less: undistributed earnings allocated to participating securities	0	0	0	0
Net loss attributable to SLGOP common unitholders (numerator for basic earnings per unit)	(29,518)	(13,110)	(121,448)	(36,893)
Add back: dilutive effect of earnings allocated to participating securities and contingently issuable shares	0	0	0	0
Add back: undistributed earnings allocated to participating securities	0	0	0	0
Loss attributable to SL Green common stockholders (numerator for diluted earnings per share)	$ (29,518)	$ (13,110)	$ (121,448)	$ (36,893)
Denominator
Basic weighted average common units outstanding (in shares)	75,525	74,455	75,596	74,491
Stock-based compensation plans (in shares)	0	0	0	0
Contingently issuable units (in shares)	0	0	0	0
Diluted weighted average common units outstanding (in shares)	75,525	74,455	75,596	74,491

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