Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Activities
Net income	$ 127,114	$ 52,769
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	70,779	71,085
Equity in net loss from unconsolidated joint ventures	12,814	5,234
Distributions of cumulative earnings from unconsolidated joint ventures	108	425
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate	0	(17,166)
Purchase price and other fair value adjustments	0	2,041
(Gain) loss on sale of real estate, net	(72,636)	1,049
Loan loss reserves and other investment reserves, net of recoveries	11,248	0
Deferred rents receivable	3,717	(1,114)
Non-cash lease expense	3,390	3,381
Other non-cash adjustments	1,110	9,027
Changes in operating assets and liabilities:
Tenant and other receivables	(44,960)	(4,759)
Related party receivables	(4,711)	(1,270)
Deferred lease costs	(8,603)	(13,111)
Other assets	(48,130)	(40,218)
Accounts payable, accrued expenses, other liabilities and security deposits	(13,877)	(12,915)
Deferred revenue	7,622	10,721
Change in lease liability - operating leases	(2,959)	(2,866)
Net cash provided by operating activities	42,026	62,313
Investing Activities
Acquisitions of real estate property	(86,846)	0
Additions to land, buildings and improvements	(101,726)	(39,524)
Acquisition deposits and deferred purchase price	0	(4,910)
Investments in unconsolidated joint ventures	(8,906)	(73,351)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	53,516	23,664
Net proceeds from disposition of real estate/joint venture interest	91,156	14,489
Other investments	(4,786)	(1,056)
Origination of debt and preferred equity investments	(223,374)	(430,034)
Repayments or redemption of debt and preferred equity investments	151,548	218,879
Net cash (used in) provided by investing activities	(129,418)	(291,843)
Financing Activities
Proceeds from mortgages and other loans payable	101,103	109,872
Repayments of mortgages and other loans payable	(102,777)	(1,127)
Proceeds from revolving credit facility and senior unsecured notes	1,125,000	520,000
Repayments of revolving credit facility and senior unsecured notes	(315,000)	(230,000)
Proceeds from stock options exercised and DRSPP issuance	166	47
Repurchase of common stock	(219,576)	(34,243)
Redemption of preferred stock	(19,392)	(15,142)
Redemption of OP units	(18,066)	(15,697)
Distributions to noncontrolling interests in other partnerships	(492)	(208)
Contributions from noncontrolling interests in other partnerships	3,814	161
Acquisition of subsidiary interest from noncontrolling interest	(1,536)	0
Distributions to noncontrolling interests in the Operating Partnership	(1,284)	(3,643)
Dividends / Distributions paid on common and preferred stock / units	(79,662)	(77,399)
Tax withholdings related to restricted share awards	(4,752)	(3,126)
Deferred loan costs	(562)	(3,367)
Net cash provided by financing activities	466,984	246,128
Net increase in cash, cash equivalents, and restricted cash	379,592	16,598
Cash, cash equivalents, and restricted cash at beginning of year	241,430	279,113
Cash, cash equivalents, and restricted cash at end of period	621,022	295,711
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Conversion of units in the Operating Partnership	84	446
Tenant improvements and capital expenditures payable	602	9,350
Reversal of assets held for sale	391,664	0
Seller financed purchases	100,000	0
Debt and preferred equity reserves	4,638	0
Removal of fully depreciated commercial real estate properties	512	4,012
Recognition of right of use assets and related lease liabilities	102,782	389,120
Total cash, cash equivalents, and restricted cash	621,022	295,711
SL Green Operating Partnership
Operating Activities
Net income	127,114	52,769
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	70,779	71,085
Equity in net loss from unconsolidated joint ventures	12,814	5,234
Distributions of cumulative earnings from unconsolidated joint ventures	108	425
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate	0	(17,166)
Purchase price and other fair value adjustments	0	2,041
(Gain) loss on sale of real estate, net	(72,636)	1,049
Loan loss reserves and other investment reserves, net of recoveries	11,248	0
Deferred rents receivable	3,717	(1,114)
Non-cash lease expense	3,390	3,381
Other non-cash adjustments	1,110	9,027
Changes in operating assets and liabilities:
Tenant and other receivables	(44,960)	(4,759)
Related party receivables	(4,711)	(1,270)
Deferred lease costs	(8,603)	(13,111)
Other assets	(48,130)	(40,218)
Accounts payable, accrued expenses, other liabilities and security deposits	(13,877)	(12,915)
Deferred revenue	7,622	10,721
Change in lease liability - operating leases	(2,959)	(2,866)
Net cash provided by operating activities	42,026	62,313
Investing Activities
Acquisitions of real estate property	(86,846)	0
Additions to land, buildings and improvements	(101,726)	(39,524)
Acquisition deposits and deferred purchase price	0	(4,910)
Investments in unconsolidated joint ventures	(8,906)	(73,351)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	53,516	23,664
Net proceeds from disposition of real estate/joint venture interest	91,156	14,489
Other investments	(4,786)	(1,056)
Origination of debt and preferred equity investments	(223,374)	(430,034)
Repayments or redemption of debt and preferred equity investments	151,548	218,879
Net cash (used in) provided by investing activities	(129,418)	(291,843)
Financing Activities
Proceeds from mortgages and other loans payable	101,103	109,872
Repayments of mortgages and other loans payable	(102,777)	(1,127)
Proceeds from revolving credit facility and senior unsecured notes	1,125,000	520,000
Repayments of revolving credit facility and senior unsecured notes	(315,000)	(230,000)
Proceeds from stock options exercised and DRSPP issuance	166	47
Repurchase of common stock	(219,576)	(34,243)
Redemption of preferred stock	(19,392)	(15,142)
Redemption of OP units	(18,066)	(15,697)
Distributions to noncontrolling interests in other partnerships	(492)	(208)
Contributions from noncontrolling interests in other partnerships	3,814	161
Acquisition of subsidiary interest from noncontrolling interest	(1,536)	0
Dividends / Distributions paid on common and preferred stock / units	(80,946)	(81,042)
Tax withholdings related to restricted share awards	(4,752)	(3,126)
Deferred loan costs	(562)	(3,367)
Net cash provided by financing activities	466,984	246,128
Net increase in cash, cash equivalents, and restricted cash	379,592	16,598
Cash, cash equivalents, and restricted cash at beginning of year	241,430	279,113
Cash, cash equivalents, and restricted cash at end of period	621,022	295,711
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Conversion of units in the Operating Partnership	84	446
Tenant improvements and capital expenditures payable	602	9,350
Fair value adjustment to noncontrolling interest in the Operating Partnership	38,529	28,932
Reversal of assets held for sale	391,664	0
Seller financed purchases	100,000	0
Debt and preferred equity reserves	4,638	0
Removal of fully depreciated commercial real estate properties	512	4,012
Recognition of right of use assets and related lease liabilities	102,782	389,120
Total cash, cash equivalents, and restricted cash	$ 621,022	$ 295,711