Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating Activities
Net income	$ 329,176	$ 62,734
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	217,762	331,117
Equity in net income from unconsolidated joint ventures	(9,709)	(14,104)
Distributions of cumulative earnings from unconsolidated joint ventures	10,174	19,609
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate	(136,522)	(16,166)
Purchase price and other fair value adjustments	(57,385)	0
Depreciable real estate reserves	6,691	85,336
(Gain) loss on sale of real estate, net	(6,227)	3,256
Loan loss reserves and other investment reserves, net of recoveries	1,087	0
Gain on sale of investments in marketable securities	0	(3,262)
Loss on early extinguishment of debt	2,194	0
Deferred rents receivable	(11,328)	(33,523)
Other non-cash adjustments	8,907	21,224
Changes in operating assets and liabilities:
Tenant and other receivables	3,186	(2,318)
Related party receivables	5,186	(8,238)
Deferred lease costs	(31,828)	(31,479)
Other assets	(52,172)	(58,068)
Accounts payable, accrued expenses, other liabilities and security deposits	20,715	773
Deferred revenue and land leases payable	17,638	55,361
Net cash provided by operating activities	317,545	412,252
Investing Activities
Acquisitions of real estate property	(40,279)	(25,114)
Additions to land, buildings and improvements	(163,750)	(251,906)
Investments in unconsolidated joint ventures	(298,836)	(112,697)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	208,724	279,478
Net proceeds from disposition of real estate/joint venture interest	892,350	160,649
Proceeds from sale or redemption of marketable securities	0	55,129
Other investments	991	46,955
Origination of debt and preferred equity investments	(652,309)	(935,724)
Repayments or redemption of debt and preferred equity investments	553,341	707,676
Net cash provided by (used in) investing activities	500,232	(75,554)
Financing Activities
Proceeds from mortgages and other loans payable	339,125	779,650
Repayments of mortgages and other loans payable	(351,080)	(706,056)
Proceeds from revolving credit facility and senior unsecured notes	2,205,000	1,447,800
Repayments of revolving credit facility and senior unsecured notes	(2,000,000)	(1,270,804)
Proceeds from stock options exercised and DRIP issuance	15,689	12,475
Repurchase of common stock	(760,073)	(349,991)
Redemption of preferred stock	(350)	(125)
Distributions to noncontrolling interests in other partnerships	(1,863)	(45,089)
Contributions from noncontrolling interests in other partnerships	4,900	33,202
Distributions to noncontrolling interests in the Operating Partnership	(11,469)	(10,639)
Dividends / Distributions paid on common and preferred stock / units	(237,007)	(251,701)
Other obligations related to loan participations	(3,842)	16,737
Tax withholdings related to restricted share awards	16	(3,879)
Deferred loan costs and capitalized lease obligation	(8,257)	(8,993)
Net cash used in financing activities	(809,211)	(357,413)
Net increase (decrease) in cash, cash equivalents, and restricted cash	8,566	(20,715)
Cash, cash equivalents, and restricted cash at end of period	258,592	349,252
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of units in the Operating Partnership	0	23,273
Conversion of units in the Operating Partnership for common stock	1,560	15,352
Tenant improvements and capital expenditures payable	16,246	8,926
Fair value adjustment to noncontrolling interest in Operating Partnership	7,448	2,669
Deconsolidation of subsidiaries	298,391	328,643
Transfer of assets related to assets held for sale	734,008	273,455
Transfer of liabilities related to assets held for sale	310,496	1,290
Removal of fully depreciated commercial real estate properties	115,320	11,158
Share repurchase payable	41,746	0
Total cash, cash equivalents, and restricted cash	258,592	349,252
SL Green Operating Partnership
Operating Activities
Net income	329,176	62,734
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	217,762	331,117
Equity in net income from unconsolidated joint ventures	(9,709)	(14,104)
Distributions of cumulative earnings from unconsolidated joint ventures	10,174	19,609
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate	(136,522)	(16,166)
Purchase price and other fair value adjustments	(57,385)	0
Depreciable real estate reserves	6,691	85,336
(Gain) loss on sale of real estate, net	(6,227)	3,256
Loan loss reserves and other investment reserves, net of recoveries	1,087	0
Gain on sale of investments in marketable securities	0	(3,262)
Loss on early extinguishment of debt	2,194	0
Deferred rents receivable	(11,328)	(33,523)
Other non-cash adjustments	8,907	21,224
Changes in operating assets and liabilities:
Tenant and other receivables	3,186	(2,318)
Related party receivables	5,186	(8,238)
Deferred lease costs	(31,828)	(31,479)
Other assets	(52,172)	(58,068)
Accounts payable, accrued expenses, other liabilities and security deposits	20,715	773
Deferred revenue and land leases payable	17,638	55,361
Net cash provided by operating activities	317,545	412,252
Investing Activities
Acquisitions of real estate property	(40,279)	(25,114)
Additions to land, buildings and improvements	(163,750)	(251,906)
Investments in unconsolidated joint ventures	(298,836)	(112,697)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	208,724	279,478
Net proceeds from disposition of real estate/joint venture interest	892,350	160,649
Proceeds from sale or redemption of marketable securities	0	55,129
Other investments	991	46,955
Origination of debt and preferred equity investments	(652,309)	(935,724)
Repayments or redemption of debt and preferred equity investments	553,341	707,676
Net cash provided by (used in) investing activities	500,232	(75,554)
Financing Activities
Proceeds from mortgages and other loans payable	339,125	779,650
Repayments of mortgages and other loans payable	(351,080)	(706,056)
Proceeds from revolving credit facility and senior unsecured notes	2,205,000	1,447,800
Repayments of revolving credit facility and senior unsecured notes	(2,000,000)	(1,270,804)
Proceeds from stock options exercised and DRIP issuance	15,689	12,475
Repurchase of common stock	(760,073)	(349,991)
Redemption of preferred stock	(350)	(125)
Distributions to noncontrolling interests in other partnerships	(1,863)	(45,089)
Contributions from noncontrolling interests in other partnerships	4,900	33,202
Dividends / Distributions paid on common and preferred stock / units	(248,476)	(262,340)
Other obligations related to loan participations	(3,842)	16,737
Tax withholdings related to restricted share awards	16	(3,879)
Deferred loan costs and capitalized lease obligation	(8,257)	(8,993)
Net cash used in financing activities	(809,211)	(357,413)
Net increase (decrease) in cash, cash equivalents, and restricted cash	8,566	(20,715)
Cash, cash equivalents, and restricted cash at beginning of year	250,026	369,967
Cash, cash equivalents, and restricted cash at end of period	258,592	349,252
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of units in the Operating Partnership	0	23,273
Conversion of units in the Operating Partnership for common stock	1,560	15,352
Redemption of units in the Operating Partnership for the sale of a joint venture	10,445	0
Tenant improvements and capital expenditures payable	16,246	8,926
Fair value adjustment to noncontrolling interest in Operating Partnership	7,448	2,669
Deconsolidation of subsidiaries	298,391	328,643
Transfer of assets related to assets held for sale	734,008	273,455
Transfer of liabilities related to assets held for sale	310,496	1,290
Removal of fully depreciated commercial real estate properties	115,320	11,158
Total cash, cash equivalents, and restricted cash	$ 250,026	$ 369,967