Consolidated Statement of Capital - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Partner's Capital
Accounting Standards Update				Accounting Standards Update 2016-13 [Member]
Acquisition of subsidiary interest from noncontrolling interest	$ (29,817)		$ (1,536)
DRSPP proceeds	525	$ 738	1,006
Conversion of common units			8,744
Reallocation of noncontrolling interest in the operating partnership	39,974	(9,851)	32,598
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	32,034	32,583	25,271
Repurchases of common units	(151,197)	(337,624)	(532,262)
Proceeds from stock options exercised		818
Sale of interest in partially owned entity		(4,476)
Cash distributions to noncontrolling interests	$ (4,699)	$ (6,631)	$ (78,855)
Common Stock
Increase (Decrease) in Partner's Capital
DRSPP proceeds (in units)	11	11	16
Conversion of common units			$ 1
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in units)	274	108	(33)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	$ 4	$ 2
Repurchases of common units (in units)	(1,971)	(4,474)	(8,276)
Repurchases of common units	$ (20)	$ (46)	$ (88)
Proceeds from stock options exercised (in shares)		12
Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Acquisition of subsidiary interest from noncontrolling interest	(75)		1,587
Sale of interest in partially owned entity		$ (4,476)
Cash distributions to noncontrolling interests	(4,699)	(6,631)	(78,855)
SL Green Operating Partnership
Increase (Decrease) in Partner's Capital
Beginning Balance	4,778,253	4,935,795	5,517,198
Net income	(76,952)	447,870	385,995
Acquisition of subsidiary interest from noncontrolling interest	(29,817)		(1,536)
Other comprehensive income (loss)	96,362	20,489	(38,762)
Preferred distributions	(14,950)	(14,950)	(14,950)
DRSPP proceeds	525	738	1,006
Conversion of common units			8,744
Reallocation of noncontrolling interest in the operating partnership	39,974	(9,851)	32,598
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	32,034	32,583	25,271
Repurchases of common units	(151,197)	(337,624)	(532,262)
Proceeds from stock options exercised		818
Contributions to consolidated joint venture interests	52,164	336	12,477
Sale of interest in partially owned entity		(4,476)
Cash distributions to noncontrolling interests	(4,699)	(6,631)	(78,855)
Issuance of special distribution paid in units	160,620	123,529
Cash distributions declared (none of which represented a return of capital for federal income tax purposes)	(235,395)	(410,373)	(341,945)
Ending Balance	4,646,922	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	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	$ 4,589,702	$ 4,755,078	$ 5,247,868
Beginning Balance (units)	64,105	66,474	74,672
Net income	$ (78,074)	$ 449,754	$ 371,055
Acquisition of subsidiary interest from noncontrolling interest	(29,742)		(3,123)
Preferred distributions	$ (14,950)	$ (14,950)	$ (14,950)
DRSPP proceeds (in units)	11	11	16
DRSPP proceeds	$ 525	$ 738	$ 1,006
Conversion of common units (in units)			95
Conversion of common units			$ 8,744
Reallocation of noncontrolling interest in the operating partnership	$ 39,974	$ (9,851)	$ 32,598
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in units)	274	108	(33)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	$ 32,034	$ 32,583	$ 25,271
Repurchases of common units (in units)	(1,971)	(4,474)	(8,276)
Repurchases of common units	$ (151,197)	$ (337,624)	$ (532,262)
Proceeds from stock options exercised (in shares)		12
Proceeds from stock options exercised		$ 818
Issuance of special distribution paid primarily in units (in shares)	1,961	1,974
Issuance of special distribution paid in units	$ 160,620	$ 123,529
Cash distributions declared (none of which represented a return of capital for federal income tax purposes)	(235,395)	(410,373)	(341,945)
Ending Balance	$ 4,313,497	$ 4,589,702	$ 4,755,078	$ 5,247,868
Ending Balance (units)	64,380	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)			74,672
Ending Balance				$ 5,208,684
Ending Balance (units)				74,672
SL Green Operating Partnership | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Partner's Capital
Beginning Balance	$ (46,758)	$ (67,247)	$ (28,485)
Other comprehensive income (loss)	96,362	20,489	(38,762)
Ending Balance	49,604	(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	13,377	26,032	75,883
Net income	1,122	(1,884)	14,940
Acquisition of subsidiary interest from noncontrolling interest	(75)		1,587
Contributions to consolidated joint venture interests	52,164	336	12,477
Sale of interest in partially owned entity		(4,476)
Cash distributions to noncontrolling interests	(4,699)	(6,631)	(78,855)
Ending Balance	$ 61,889	$ 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