Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Statement of Comprehensive Income [Abstract]
Net loss	$ (77,398)	$ (21,545)
Other comprehensive income (loss):
Increase (decrease) in unrealized value of derivative instruments, including SL Green's share of joint venture derivative instruments	13,833	(25,352)
Increase in unrealized value of marketable securities	1,663	695
Foreign currency translation adjustments	361	0
Other comprehensive income (loss)	15,857	(24,657)
Comprehensive loss	(61,541)	(46,202)
Net (loss) income attributable to noncontrolling interests and preferred units distributions	(3,255)	4,208
Other comprehensive (loss) income attributable to noncontrolling interests	(946)	1,619
Comprehensive loss attributable to SL Green	$ (65,742)	$ (40,375)