Consolidated Statements of Cash Flows (Partnership) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities
Net (loss) income	$ (599,337)	$ (76,303)	$ 480,632
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	255,647	223,984	228,393
Equity in net loss from unconsolidated joint ventures	76,509	57,958	55,402
Distributions of cumulative earnings from unconsolidated joint ventures	9,897	780	824
Equity in net loss on sale of interest in unconsolidated joint venture interest/real estate	13,368	131	32,757
Purchase price and other fair value adjustments	17,260	8,118	(210,070)
Depreciable real estate reserves and impairments	382,374	6,313	23,794
Loss (gain) on sale of real estate, net	32,370	84,485	(287,417)
Loan loss and other investment reserves, net of recoveries	6,890	0	2,931
Loss on early extinguishment of debt	870	0	1,551
Deferred rents receivable	(17,903)	(5,749)	(6,701)
Non-cash lease expense	20,435	22,403	17,234
Other non-cash adjustments	28,174	(5,676)	37,164
Changes in operating assets and liabilities:
Tenant and other receivables	(1,725)	14,370	(20,561)
Related party receivables	15,788	6,666	(8,727)
Deferred lease costs	(17,427)	(21,792)	(10,117)
Other assets	(1,922)	(28,204)	20,245
Accounts payable, accrued expenses, other liabilities and security deposits	11,974	(30,839)	(66,387)
Deferred revenue	8,057	18,332	(1,727)
Change in lease liability - operating leases	(11,796)	1,111	(33,241)
Net cash provided by operating activities	229,503	276,088	255,979
Investing Activities
Acquisitions of real estate property	0	(64,491)	(152,791)
Additions to land, buildings and improvements	(259,663)	(300,770)	(302,486)
Investments in unconsolidated joint ventures	(184,481)	(184,518)	(88,872)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	140,569	141,742	770,604
Net proceeds from disposition of real estate/joint venture interest	557,611	626,364	651,594
Cash and restricted cash assumed from acquisition of real estate investment	0	60,494	0
Cash assumed from consolidation of real estate investment	0	0	9,475
Proceeds from sale or redemption of marketable securities	0	15,626	4,528
Purchases of marketable securities	0	0	(10,000)
Other investments	(17,334)	1,432	40,200
Origination of debt and preferred equity investments	(65,357)	(51,367)	(95,695)
Repayments or redemption of debt and preferred equity investments	0	181,293	167,024
Net cash provided by investing activities	171,345	425,805	993,581
Financing Activities
Proceeds from mortgages and other loans payable	0	381,980	39,689
Repayments of mortgages and other loans payable	(25,826)	(292,364)	(375,044)
Proceeds from revolving credit facility, term loans and senior unsecured notes	538,000	1,524,000	1,488,000
Repayments of revolving credit facility, term loans and senior unsecured notes	(828,000)	(1,864,000)	(1,808,000)
Proceeds from stock options exercised and DRSPP issuance	525	525	1,556
Repurchase of common units	0	(151,197)	(341,403)
Redemption of preferred units	(11,700)	(17,967)	(6,040)
Redemption of OP units	(9,076)	(40,901)	(25,703)
Distributions to noncontrolling interests in other partnerships	(2,777)	(4,699)	(6,631)
Contributions from noncontrolling interests in other partnerships	6,932	52,164	336
Acquisition of subsidiary interest from noncontrolling interest	0	(29,817)	0
Distributions paid on common and preferred units	(230,931)	(262,136)	(271,075)
Other obligation related to secured borrowing	129,656	77,874	51,862
Tax withholdings related to restricted share awards	0	(3,915)	(2,990)
Deferred loan costs	(1,407)	(8,098)	(13,745)
Principal payments on financing lease liabilities	0	0	(434)
Net cash used in financing activities	(449,383)	(654,823)	(1,285,371)
Net (decrease) increase in cash, cash equivalents, and restricted cash	(48,535)	47,070	(35,811)
Cash, cash equivalents, and restricted cash at beginning of year	384,054	336,984	372,795
Cash, cash equivalents, and restricted cash at end of period	335,519	384,054	336,984
Supplemental cash flow disclosures:
Interest paid	229,119	169,519	152,773
Income taxes paid	7,815	5,358	4,405
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Redemption of units in the Operating Partnership for a joint venture sale	0	0	27,586
Exchange of preferred equity investment for real estate or equity in joint venture	0	190,652	0
Exchange of debt investment for real estate or equity in joint venture	349,946	193,995	9,468
Assumption of mortgage and mezzanine loans	0	1,712,750	60,000
Tenant improvements and capital expenditures payable	0	18,518	7,580
Fair value adjustment to noncontrolling interest in the Operating Partnership	15,486	39,974	9,851
Investment in joint venture	0	47,135	0
Deconsolidation of a subsidiary	101,351	0	66,837
Deconsolidation of subsidiary debt	1,712,750	0	510,000
Debt and preferred equity investments	0	302	8,372
Transfer of assets related to assets held for sale	0	0	140,855
Transfer of liabilities related to assets held for sale	0	0	64,120
Extinguishment of debt in connection with property dispositions	0	0	53,548
Consolidation of real estate investment	0	0	119,444
Removal of fully depreciated commercial real estate properties	16,313	30,359	19,831
Sale of interest in partially owned entity	0	0	4,476
Contribution to consolidated joint venture by noncontrolling interest	8,134	0	0
Distributions to noncontrolling interests	0	0	358
Share repurchase or redemption payable	9,513	0	0
Recognition of right of use assets and related lease liabilities	0	57,938	537,344
Cash and cash equivalents	221,823	203,273	251,417
Restricted cash	113,696	180,781	85,567
Total cash, cash equivalents, and restricted cash	335,519	384,054	336,984
SL Green Operating Partnership
Operating Activities
Net (loss) income	(599,337)	(76,303)	480,632
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	255,647	223,984	228,393
Equity in net loss from unconsolidated joint ventures	76,509	57,958	55,402
Distributions of cumulative earnings from unconsolidated joint ventures	9,897	780	824
Equity in net loss on sale of interest in unconsolidated joint venture interest/real estate	13,368	131	32,757
Purchase price and other fair value adjustments	17,260	8,118	(210,070)
Depreciable real estate reserves and impairments	382,374	6,313	23,794
Loss (gain) on sale of real estate, net	32,370	84,485	(287,417)
Loan loss and other investment reserves, net of recoveries	6,890	0	2,931
Loss on early extinguishment of debt	870	0	1,551
Deferred rents receivable	(17,903)	(5,749)	(6,701)
Non-cash lease expense	20,435	22,403	17,234
Other non-cash adjustments	28,174	(5,676)	37,164
Changes in operating assets and liabilities:
Tenant and other receivables	(1,725)	14,370	(20,561)
Related party receivables	15,788	6,666	(8,727)
Deferred lease costs	(17,427)	(21,792)	(10,117)
Other assets	(1,922)	(28,204)	20,245
Accounts payable, accrued expenses, other liabilities and security deposits	11,974	(30,839)	(66,387)
Deferred revenue	8,057	18,332	(1,727)
Change in lease liability - operating leases	(11,796)	1,111	(33,241)
Net cash provided by operating activities	229,503	276,088	255,979
Investing Activities
Acquisitions of real estate property	0	(64,491)	(152,791)
Additions to land, buildings and improvements	(259,663)	(300,770)	(302,486)
Investments in unconsolidated joint ventures	(184,481)	(184,518)	(88,872)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	140,569	141,742	770,604
Net proceeds from disposition of real estate/joint venture interest	557,611	626,364	651,594
Cash and restricted cash assumed from acquisition of real estate investment	0	60,494	0
Cash assumed from consolidation of real estate investment	0	0	9,475
Proceeds from sale or redemption of marketable securities	0	15,626	4,528
Purchases of marketable securities	0	0	(10,000)
Other investments	(17,334)	1,432	40,200
Origination of debt and preferred equity investments	(65,357)	(51,367)	(95,695)
Repayments or redemption of debt and preferred equity investments	0	181,293	167,024
Net cash provided by investing activities	171,345	425,805	993,581
Financing Activities
Proceeds from mortgages and other loans payable	0	381,980	39,689
Repayments of mortgages and other loans payable	(25,826)	(292,364)	(375,044)
Proceeds from revolving credit facility, term loans and senior unsecured notes	538,000	1,524,000	1,488,000
Repayments of revolving credit facility, term loans and senior unsecured notes	(828,000)	(1,864,000)	(1,808,000)
Proceeds from stock options exercised and DRSPP issuance	525	525	1,556
Repurchase of common units	0	(151,197)	(341,403)
Redemption of preferred units	(11,700)	(17,967)	(6,040)
Redemption of OP units	(9,076)	(40,901)	(25,703)
Distributions to noncontrolling interests in other partnerships	(2,777)	(4,699)	(6,631)
Contributions from noncontrolling interests in other partnerships	6,932	52,164	336
Acquisition of subsidiary interest from noncontrolling interest	0	(29,817)	0
Distributions paid on common and preferred units	(245,710)	(278,408)	(286,824)
Other obligation related to secured borrowing	129,656	77,874	51,862
Tax withholdings related to restricted share awards	0	(3,915)	(2,990)
Deferred loan costs	(1,407)	(8,098)	(13,745)
Principal payments on financing lease liabilities	0	0	(434)
Net cash used in financing activities	(449,383)	(654,823)	(1,285,371)
Net (decrease) increase in cash, cash equivalents, and restricted cash	(48,535)	47,070	(35,811)
Cash, cash equivalents, and restricted cash at beginning of year	384,054	336,984	372,795
Cash, cash equivalents, and restricted cash at end of period	335,519	384,054	336,984
Supplemental cash flow disclosures:
Interest paid	229,119	169,519	152,773
Income taxes paid	7,815	5,358	4,405
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Redemption of units in the Operating Partnership for a joint venture sale	0	0	27,586
Exchange of preferred equity investment for real estate or equity in joint venture	0	190,652	0
Exchange of debt investment for real estate or equity in joint venture	349,946	193,995	9,468
Assumption of mortgage and mezzanine loans	0	1,712,750	60,000
Issuance of special distribution paid in units	0	160,620	121,418
Tenant improvements and capital expenditures payable	0	18,518	7,580
Fair value adjustment to noncontrolling interest in the Operating Partnership	15,486	39,974	9,851
Investment in joint venture	0	47,135	0
Deconsolidation of a subsidiary	101,351	0	66,837
Deconsolidation of subsidiary debt	1,712,750	0	510,000
Debt and preferred equity investments	0	302	8,372
Transfer of assets related to assets held for sale	0	0	140,855
Transfer of liabilities related to assets held for sale	0	0	64,120
Extinguishment of debt in connection with property dispositions	0	0	53,548
Consolidation of real estate investment	0	0	119,444
Removal of fully depreciated commercial real estate properties	16,313	30,359	19,831
Sale of interest in partially owned entity	0	0	4,476
Contribution to consolidated joint venture by noncontrolling interest	8,134	0	0
Distributions to noncontrolling interests	0	0	358
Share repurchase or redemption payable	9,513	0	0
Recognition of right of use assets and related lease liabilities	0	57,938	537,344
Cash and cash equivalents	221,823	203,273	251,417
Restricted cash	113,696	180,781	85,567
Total cash, cash equivalents, and restricted cash	$ 335,519	$ 384,054	$ 336,984