Consolidated Statement of Capital shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares
Increase (Decrease) in Partner's Capital
Accounting Standards Update				Accounting Standards Update 2016-13
Acquisition of subsidiary interest from noncontrolling interest			$ (1,536)	$ (25,845)
DRSPP proceeds		$ 738	1,006	334
Conversion of common units			8,744	471
Reallocation of noncontrolling interest in the operating partnership		(9,851)	32,598	(34,320)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings		32,583	25,271	25,763
Repurchases of common units		(337,624)	(532,262)	(384,399)
Proceeds from stock options exercised		818
Sale of interest in partially owned entity		(4,476)
Cash distributions to noncontrolling interests		$ (6,631)	$ (78,855)	$ (478)
Common Stock
Increase (Decrease) in Partner's Capital
DRSPP proceeds (in units) | shares	[1]	11	16	4
DRSPP proceeds
Conversion of common units			$ 1
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in units) | shares	[1]	108	(33)	99
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings		$ 2	$ 0	$ 2
Repurchases of common units (in units) | shares	[1]	(4,474)	(8,276)	(4,333)
Repurchases of common units		$ (46)	$ (88)	$ (46)
Proceeds from stock options exercised (in shares) | shares	[1]	12
Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Acquisition of subsidiary interest from noncontrolling interest			1,587	(25,276)
Sale of interest in partially owned entity		$ (4,476)
Cash distributions to noncontrolling interests		(6,631)	(78,855)	(478)
SL Green Operating Partnership
Increase (Decrease) in Partner's Capital
Beginning Balance		4,935,795	5,517,198	5,947,855
Net income		447,870	385,995	267,275
Acquisition of subsidiary interest from noncontrolling interest			(1,536)	(25,845)
Other comprehensive income (loss)		20,489	(38,762)	(43,593)
Preferred distributions		(14,950)	(14,950)	(14,950)
DRSPP proceeds		738	1,006	334
Conversion of common units			8,744	471
Reallocation of noncontrolling interest in the operating partnership		(9,851)	32,598	(34,320)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings		32,583	25,271	25,763
Repurchases of common units		(337,624)	(532,262)	(384,399)
Proceeds from stock options exercised		818
Contributions to consolidated joint venture interests		336	12,477	58,462
Sale of interest in partially owned entity		(4,476)
Cash distributions to noncontrolling interests		(6,631)	(78,855)	(478)
Issuance of special distribution paid primarily in units		123,529
Cash distributions declared (none of which represented a return of capital for federal income tax purposes)		(410,373)	(341,945)	(279,377)
Ending Balance		4,778,253	4,935,795	5,517,198
SL Green Operating Partnership | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Partner's Capital
Beginning Balance			(39,184)
Ending Balance				(39,184)
SL Green Operating Partnership | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Partner's Capital
Beginning Balance			5,478,014
Ending Balance				5,478,014
SL Green Operating Partnership | Preferred Units | Series I Preferred Stock
Increase (Decrease) in Partner's Capital
Beginning Balance		221,932	221,932	221,932
Ending Balance		221,932	221,932	221,932
SL Green Operating Partnership | Preferred Units | Series I Preferred Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Partner's Capital
Beginning Balance			221,932
Ending Balance				221,932
SL Green Operating Partnership | Common Stock | Partners' Interest
Increase (Decrease) in Partner's Capital
Beginning Balance		$ 4,755,078	$ 5,247,868	$ 5,664,481
Beginning Balance (units) | shares	[2]	66,474	74,672	78,897
Net income		$ 449,754	$ 371,055	$ 270,434
Acquisition of subsidiary interest from noncontrolling interest			(3,123)	(569)
Preferred distributions		$ (14,950)	$ (14,950)	$ (14,950)
DRSPP proceeds (in units) | shares	[2]	11	16	4
DRSPP proceeds		$ 738	$ 1,006	$ 334
Conversion of common units (in units) | shares	[2]		95	5
Conversion of common units			$ 8,744	$ 471
Reallocation of noncontrolling interest in the operating partnership		$ (9,851)	$ 32,598	$ (34,320)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in units) | shares	[2]	108	(33)	99
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings		$ 32,583	$ 25,271	$ 25,763
Repurchases of common units (in units) | shares	[2]	(4,474)	(8,276)	(4,333)
Repurchases of common units		$ (337,624)	$ (532,262)	$ (384,399)
Proceeds from stock options exercised (in shares) | shares	[2]	12
Proceeds from stock options exercised		$ 818
Issuance of special distribution paid primarily in units (in shares) | shares	[2]	1,974
Issuance of special distribution paid primarily in units		$ 123,529
Cash distributions declared (none of which represented a return of capital for federal income tax purposes)		(410,373)	(341,945)	(279,377)
Ending Balance		$ 4,589,702	$ 4,755,078	$ 5,247,868
Ending Balance (units) | shares	[2]	64,105	66,474	74,672
SL Green Operating Partnership | Common Stock | Partners' Interest | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Partner's Capital
Beginning Balance			$ (39,184)
Ending Balance				$ (39,184)
SL Green Operating Partnership | Common Stock | Partners' Interest | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Partner's Capital
Beginning Balance			$ 5,208,684
Beginning Balance (units) | shares	[2]		74,672
Ending Balance				$ 5,208,684
Ending Balance (units) | shares	[2]			74,672
SL Green Operating Partnership | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Partner's Capital
Beginning Balance		$ (67,247)	$ (28,485)	$ 15,108
Other comprehensive income (loss)		20,489	(38,762)	(43,593)
Ending Balance		(46,758)	(67,247)	(28,485)
SL Green Operating Partnership | Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Partner's Capital
Beginning Balance			(28,485)
Ending Balance				(28,485)
SL Green Operating Partnership | Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Beginning Balance		26,032	75,883	46,334
Net income		(1,884)	14,940	(3,159)
Acquisition of subsidiary interest from noncontrolling interest			1,587	(25,276)
Contributions to consolidated joint venture interests		336	12,477	58,462
Sale of interest in partially owned entity		(4,476)
Cash distributions to noncontrolling interests		(6,631)	(78,855)	(478)
Ending Balance		$ 13,377	26,032	75,883
SL Green Operating Partnership | Noncontrolling Interests | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Partner's Capital
Beginning Balance			$ 75,883
Ending Balance				$ 75,883

[1] On January 18, 2022, we completed a reverse stock split whereby every 1.03060 SL Green common share was combined into 1 SL Green common share. We have retroactively adjusted the outstanding share counts, share activity, cash distributions declared, and earnings per share, as if the reverse split occurred on December 31, 2018.

[2] On January 18, 2022, we completed a reverse stock split whereby every 1.03060 SL Green Operating Partnership common unit was combined into 1 SL Green Operating Partnership common unit. We have retroactively adjusted the outstanding unit counts, unit activity, cash distributions declared, and earnings per units, as if the reverse split occurred on December 31, 2018