Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities
Net income	$ 32,503	$ 55,636
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	187,240	114,955
Equity in net income from unconsolidated joint ventures	(10,096)	(4,030)
Distributions of cumulative earnings from unconsolidated joint ventures	8,891	15,489
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate	(9,915)	0
Gain on sale of real estate	(13,773)	0
Gain on sale of discontinued operations	0	(12,983)
Loss on early extinguishment of debt	0	49
Deferred rents receivable	(652)	(32,367)
Other non-cash adjustments	(14,920)	4,590
Changes in operating assets and liabilities:
Restricted cash—operations	(5,318)	(1,652)
Tenant and other receivables	7,829	7,096
Related party receivables	(4,503)	(353)
Deferred lease costs	(13,133)	(11,017)
Other assets	(46,736)	(38,280)
Accounts payable, accrued expenses and other liabilities and security deposits	(20,630)	(20,230)
Deferred revenue and land leases payable	17,303	14,056
Net cash provided by operating activities	114,090	90,959
Investing Activities
Acquisitions of real estate property	(37,728)	(6,290)
Additions to land, buildings and improvements	(62,500)	(47,117)
Escrowed cash—capital improvements/acquisition deposits/deferred purchase price	60,059	(3,084)
Investments in unconsolidated joint ventures	(6,603)	(83,772)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	95,004	45,546
Net proceeds from disposition of real estate/joint venture interest	139,594	485,540
Proceeds from sale of marketable securities	0	133
Purchases of marketable securities	0	(7,769)
Other investments	(4,103)	(5,424)
Origination of debt and preferred equity investments	(117,119)	(174,420)
Repayments or redemption of debt and preferred equity investments	272,253	26,954
Net cash provided by investing activities	338,857	230,297
Financing Activities
Proceeds from mortgages and other loans payable	227,892	0
Repayments of mortgages and other loans payable	(127,695)	(481,608)
Proceeds from revolving credit facility and senior unsecured notes	520,000	665,000
Repayments of revolving credit facility and senior unsecured notes	(994,296)	(530,000)
Proceeds from stock options exercised and DRIP issuance	1,256	109,840
Proceeds from sale of common stock	0	120,597
Redemption of preferred stock	(440)	(200)
Distributions to noncontrolling interests in other partnerships	(7,905)	(110,867)
Contributions from noncontrolling interests in other partnerships	934	0
Distributions to noncontrolling interests in the Operating Partnership	(2,881)	(2,349)
Dividends/Distributions paid on common and preferred stock/units	(78,103)	(62,903)
Other obligations related to mortgage loan participations	76,500	25,000
Deferred loan costs and capitalized lease obligation	(7,403)	(4,405)
Net cash used in financing activities	(392,141)	(271,895)
Net increase in cash and cash equivalents	60,806	49,361
Cash and cash equivalents at beginning of year	255,399	281,409
Cash and cash equivalents at end of period	316,205	330,770
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of common stock as deferred compensation	2,195	1,306
Issuance of units in the operating partnership	18,140	22,114
Redemption of units in the operating partnership	7,153	37,407
Derivative instruments at fair value	8,141	4,426
Exchange of debt investment for equity in joint venture	68,581	10,151
Transfer of restricted cash to operating cash and cash equivalents as a result of sale	0	21,578
Acquisition of subsidiary interest from noncontrolling interest	0	3,500
Tenant improvements and capital expenditures payable	18,165	17,664
Fair value adjustment to noncontrolling interest in operating partnership	25,867	45,456
Transfer of assets to assets held for sale	1,891,575	0
Transfer of liabilities related to assets held for sale	1,612,001	0
Deferred leasing payable	1,699	2,372
Removal of fully depreciated commercial real estate properties	4,822	0
SL Green Operating Partnership
Operating Activities
Net income	32,503	55,636
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	187,240	114,955
Equity in net income from unconsolidated joint ventures	(10,096)	(4,030)
Distributions of cumulative earnings from unconsolidated joint ventures	8,891	15,489
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate	(9,915)	0
Gain on sale of real estate	(13,773)	0
Gain on sale of discontinued operations	0	(12,983)
Loss on early extinguishment of debt	0	49
Deferred rents receivable	(652)	(32,367)
Other non-cash adjustments	(14,920)	4,590
Changes in operating assets and liabilities:
Restricted cash—operations	(5,318)	(1,652)
Tenant and other receivables	7,829	7,096
Related party receivables	(4,503)	(353)
Deferred lease costs	(13,133)	(11,017)
Other assets	(46,736)	(38,280)
Accounts payable, accrued expenses and other liabilities and security deposits	(20,630)	(20,230)
Deferred revenue and land leases payable	17,303	14,056
Net cash provided by operating activities	114,090	90,959
Investing Activities
Acquisitions of real estate property	(37,728)	(6,290)
Additions to land, buildings and improvements	(62,500)	(47,117)
Escrowed cash—capital improvements/acquisition deposits/deferred purchase price	60,059	(3,084)
Investments in unconsolidated joint ventures	(6,603)	(83,772)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	95,004	45,546
Net proceeds from disposition of real estate/joint venture interest	139,594	485,540
Proceeds from sale of marketable securities	0	133
Purchases of marketable securities	0	(7,769)
Other investments	(4,103)	(5,424)
Origination of debt and preferred equity investments	(117,119)	(174,420)
Repayments or redemption of debt and preferred equity investments	272,253	26,954
Net cash provided by investing activities	338,857	230,297
Financing Activities
Proceeds from mortgages and other loans payable	227,892	0
Repayments of mortgages and other loans payable	(127,695)	(481,608)
Proceeds from revolving credit facility and senior unsecured notes	520,000	665,000
Repayments of revolving credit facility and senior unsecured notes	(994,296)	(530,000)
Proceeds from stock options exercised and DRIP issuance	1,256	109,840
Proceeds from sale of common stock	0	120,597
Redemption of preferred stock	(440)	(200)
Distributions to noncontrolling interests in other partnerships	(7,905)	(110,867)
Contributions from noncontrolling interests in other partnerships	934	0
Dividends/Distributions paid on common and preferred stock/units	(80,984)	(65,252)
Other obligations related to mortgage loan participations	76,500	25,000
Deferred loan costs and capitalized lease obligation	(7,403)	(4,405)
Net cash used in financing activities	(392,141)	(271,895)
Net increase in cash and cash equivalents	60,806	49,361
Cash and cash equivalents at beginning of year	255,399	281,409
Cash and cash equivalents at end of period	316,205	330,770
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of common stock as deferred compensation	2,195	1,306
Issuance of units in the operating partnership	18,140	22,114
Redemption of units in the operating partnership	7,153	37,407
Derivative instruments at fair value	8,141	4,426
Exchange of debt investment for equity in joint venture	68,581	10,151
Transfer of restricted cash to operating cash and cash equivalents as a result of sale	0	21,578
Acquisition of subsidiary interest from noncontrolling interest	0	3,500
Tenant improvements and capital expenditures payable	18,165	17,664
Fair value adjustment to noncontrolling interest in operating partnership	25,867	0
Transfer of assets to assets held for sale	1,891,575	0
Transfer of liabilities related to assets held for sale	1,612,001	0
Deferred leasing payable	1,699	2,372
Removal of fully depreciated commercial real estate properties	4,822	0
Preferred Units
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of preferred units relating to the real estate acquisition	22,750	0
Issuance of preferred units (Stonehenge)	0	40,000
Preferred Units | SL Green Operating Partnership
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of preferred units relating to the real estate acquisition	22,750	0
Issuance of preferred units (Stonehenge)	$ 0	$ 40,000