Consolidated Statements of Capital - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Increase (Decrease) in Partner's Capital
DRSPP proceeds	$ 251	$ 52,308	$ 525
Measurement adjustment for redeemable noncontrolling interest	18,863	(107,631)	(15,486)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	18,546	26,848	35,573
Proceeds from issuance of common stock	(1,094)	386,790
Contributions to consolidated joint venture interests	4,757	6,656	15,066
Contributions to debt fund investments	194,292
Consolidation of partially owned entity		59,452
Cash distributions to noncontrolling interests	$ (3,126)	$ (11,053)	$ (2,777)
Common Stock
Increase (Decrease) in Partner's Capital
DRSPP proceeds (in units)	4	729	17
DRSPP proceeds		$ 7
Conversion of common units (in units)	47	124
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in units)	11	455	329
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings		$ 4	$ 4
Proceeds from issuance of common stock (in shares)		5,063
Proceeds from issuance of common stock		$ 51
Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	698
Contributions to consolidated joint venture interests	4,757	6,656	15,066
Contributions to debt fund investments	194,292
Consolidation of partially owned entity		59,452
Cash distributions to noncontrolling interests	(3,126)	(11,053)	(2,777)
SL Green Operating Partnership
Increase (Decrease) in Partner's Capital
Beginning balance	4,069,951	3,855,925	4,646,922
Net income (loss)	(97,881)	21,082	(569,127)
Acquisition of subsidiary interest from noncontrolling interest	(15,631)	(9,216)
Other comprehensive income (loss)	(40,394)	719	(32,127)
Perpetual preferred unit dividends	(14,950)	(14,950)	(14,950)
DRSPP proceeds	251	52,308	525
Measurement adjustment for redeemable noncontrolling interest	18,863	(107,631)	(15,486)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	18,546	26,848	35,573
Proceeds from issuance of common stock	(1,094)	386,790
Contributions to consolidated joint venture interests	4,757	6,656	15,066
Contributions to debt fund investments	194,292
Distributions from debt fund investments	(21,354)
Consolidation of partially owned entity		59,452
Cash distributions to noncontrolling interests	(3,126)	(11,053)	(2,777)
Cash distributions declared	(199,782)	(196,979)	(207,694)
Ending balance	3,912,448	4,069,951	3,855,925
SL Green Operating Partnership | Preferred Units | Series I Preferred Units
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 | Common Stock | Partners' Interest
Increase (Decrease) in Partner's Capital
Beginning balance	$ 3,711,172	$ 3,546,906	$ 4,313,497
Beginning balance (units)	71,097	64,726	64,380
Net income (loss)	$ (96,910)	$ 22,010	$ (564,559)
Acquisition of subsidiary interest from noncontrolling interest	36,023	(4,130)
Perpetual preferred unit dividends	$ (14,950)	$ (14,950)	$ (14,950)
DRSPP proceeds (in units)	4	729	17
DRSPP proceeds	$ 251	$ 52,308	$ 525
Conversion of common units (in units)	47	124
Measurement adjustment for redeemable noncontrolling interest	$ 18,863	$ (107,631)	$ (15,486)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in units)	11	455	329
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	$ 17,848	$ 26,848	$ 35,573
Proceeds from issuance of common stock (in shares)	0	5,063
Proceeds from issuance of common stock	$ (1,094)	$ 386,790
Cash distributions declared	(199,782)	(196,979)	(207,694)
Ending balance	$ 3,471,421	$ 3,711,172	$ 3,546,906
Ending balance (units)	71,159	71,097	64,726
SL Green Operating Partnership | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Partner's Capital
Beginning balance	$ 18,196	$ 17,477	$ 49,604
Other comprehensive income (loss)	(40,394)	719	(32,127)
Ending balance	(22,198)	18,196	17,477
SL Green Operating Partnership | Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Beginning balance	118,651	69,610	61,889
Net income (loss)	(971)	(928)	(4,568)
Acquisition of subsidiary interest from noncontrolling interest	(51,654)	(5,086)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	698
Contributions to consolidated joint venture interests	4,757	6,656	15,066
Contributions to debt fund investments	194,292
Distributions from debt fund investments	(21,354)
Consolidation of partially owned entity		59,452
Cash distributions to noncontrolling interests	(3,126)	(11,053)	(2,777)
Ending balance	$ 241,293	$ 118,651	$ 69,610