Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Rental revenue, net	$ 1,323,767	$ 1,245,981	$ 1,121,066
Escalation and reimbursement	196,858	178,512	164,376
Investment income	213,008	181,128	178,815
Other income	130,348	57,208	55,721
Total revenues	1,863,981	1,662,829	1,519,978
Expenses
Operating expenses, including $21,890 in 2016, $20,071 in 2015, and $19,308 in 2014 of related party expenses	312,859	301,624	282,283
Real estate taxes	248,388	232,702	217,843
Ground rent	33,261	32,834	32,307
Interest expense, net of interest income	321,199	323,870	317,400
Amortization of deferred financing costs	24,564	27,348	22,377
Depreciation and amortization	821,041	560,887	371,610
Transaction related costs	7,528	11,430	8,707
Marketing, general and administrative	99,759	94,873	92,488
Total expenses	1,868,599	1,585,568	1,345,015
(Loss) income from continuing operations before equity in net income from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture/real estate, purchase price fair value adjustment, gain on sale of real estate, depreciable real estate reserves, (loss) gain on sale of marketable securities and loss on early extinguishment of debt	(4,618)	77,261	174,963
Equity in net income from unconsolidated joint ventures	11,874	13,028	26,537
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	44,009	15,844	123,253
Purchase price fair value adjustment	0	40,078	67,446
Gain on sale of real estate, net	238,116	175,974	0
Depreciable real estate reserves	(10,387)	(19,226)	0
(Loss) gain on sale of investment in marketable securities	(83)	0	3,895
Loss on early extinguishment of debt	0	(49)	(32,365)
Income from continuing operations	278,911	302,910	363,729
Net income from discontinued operations	0	427	19,075
Gain on sale of discontinued operations	0	14,122	163,059
Net income	278,911	317,459	545,863
Net income attributable to noncontrolling interests:
Noncontrolling interests in the Operating Partnership	(10,136)	(10,565)	(18,467)
Net income attributable to noncontrolling interests in other partnerships	(7,644)	(15,843)	(6,590)
Preferred unit distributions	(11,235)	(6,967)	(2,750)
Net income (loss) attributable to SL Green/SLGOP	249,896	284,084	518,056
Preferred stock/unit redemption costs	0	0	0
Perpetual preferred stock dividends	(14,950)	(14,952)	(14,952)
Amounts attributable to SL Green common stockholders:
(Loss) income from continuing operations before purchase price fair value adjustment, gains on sale and discontinued operations	(25,552)	50,502	143,466
Purchase price fair value adjustment	0	38,563	65,059
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	42,189	15,245	118,891
Net income from discontinued operations	0	411	18,400
Gain on sale of discontinued operations	0	13,588	157,288
Gain on sale of real estate	228,266	169,322	0
Depreciable real estate reserves	(9,957)	(18,499)	0
Net income attributable to SL Green common stockholders	$ 234,946	$ 269,132	$ 503,104
Basic earnings per share:
Income from continuing operations before purchase price fair value adjustment, gains on sale and discontinued operations (usd per share)	$ (0.26)	$ 0.51	$ 1.50
Purchase price fair value adjustment (usd per share)	0.00	0.39	0.68
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (usd per share)	0.42	0.15	1.24
Net income from discontinued operations (usd per share)	0.00	0.00	0.19
Gain on sale of discontinued operations (usd per share)	0.00	0.14	1.64
Gain on sale of real estate (in dollars per share)	2.29	1.71	0.00
Depreciable real estate reserves (in dollars per share)	(0.10)	(0.19)	0.00
Net income attributable to SL Green common stockholders (usd per share)	2.35	2.71	5.25
Diluted earnings per share:
Income from continuing operations before purchase price fair value adjustment, gains on sale and discontinued operations (usd per share)	(0.25)	0.51	1.52
Purchase price fair value adjustment (usd per share)	0.00	0.39	0.65
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (usd per share)	0.42	0.15	1.24
Net income from discontinued operations (usd per share)	0.00	0.00	0.19
Gain on sale of discontinued operations (usd per share)	0.00	0.14	1.63
Gain on sale of real estate (in dollars per share)	2.27	1.70	0.00
Depreciable real estate reserves (in dollars per share)	(0.10)	(0.19)	0.00
Net income attributable to SL Green common stockholders (usd per share)	$ 2.34	$ 2.70	$ 5.23
Basic weighted average common shares outstanding (in shares)	100,185	99,345	95,774
Diluted weighted average common shares and common share equivalents outstanding (in shares)	104,881	103,734	99,696
SL Green Operating Partnership
Revenues
Rental revenue, net	$ 1,323,767	$ 1,245,981	$ 1,121,066
Escalation and reimbursement	196,858	178,512	164,376
Investment income	213,008	181,128	178,815
Other income	130,348	57,208	55,721
Total revenues	1,863,981	1,662,829	1,519,978
Expenses
Operating expenses, including $21,890 in 2016, $20,071 in 2015, and $19,308 in 2014 of related party expenses	312,859	301,624	282,283
Real estate taxes	248,388	232,702	217,843
Ground rent	33,261	32,834	32,307
Interest expense, net of interest income	321,199	323,870	317,400
Amortization of deferred financing costs	24,564	27,348	22,377
Depreciation and amortization	821,041	560,887	371,610
Transaction related costs	7,528	11,430	8,707
Marketing, general and administrative	99,759	94,873	92,488
Total expenses	1,868,599	1,585,568	1,345,015
(Loss) income from continuing operations before equity in net income from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture/real estate, purchase price fair value adjustment, gain on sale of real estate, depreciable real estate reserves, (loss) gain on sale of marketable securities and loss on early extinguishment of debt	(4,618)	77,261	174,963
Equity in net income from unconsolidated joint ventures	11,874	13,028	26,537
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	44,009	15,844	123,253
Purchase price fair value adjustment	0	40,078	67,446
Gain on sale of real estate, net	238,116	175,974	0
Depreciable real estate reserves	(10,387)	(19,226)	0
(Loss) gain on sale of investment in marketable securities	(83)	0	3,895
Loss on early extinguishment of debt	0	(49)	(32,365)
Income from continuing operations	278,911	302,910	363,729
Net income from discontinued operations	0	427	19,075
Gain on sale of discontinued operations	0	14,122	163,059
Net income	278,911	317,459	545,863
Net income attributable to noncontrolling interests:
Net income attributable to noncontrolling interests in other partnerships	(7,644)	(15,843)	(6,590)
Preferred unit distributions	(11,235)	(6,967)	(2,750)
Net income (loss) attributable to SL Green/SLGOP	260,032	294,649	536,523
Preferred stock/unit redemption costs	0	0	0
Perpetual preferred stock dividends	(14,950)	(14,952)	(14,952)
Net income attributable to SLGOP common unitholders	245,082	279,697	521,571
Amounts attributable to SL Green common stockholders:
(Loss) income from continuing operations before purchase price fair value adjustment, gains on sale and discontinued operations	(26,656)	52,478	148,738
Purchase price fair value adjustment	0	40,078	67,446
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	44,009	15,844	123,253
Net income from discontinued operations	0	427	19,075
Gain on sale of discontinued operations	0	14,122	163,059
Gain on sale of real estate	238,116	175,974	0
Depreciable real estate reserves	$ (10,387)	$ (19,226)	$ 0
Basic earnings per share:
Income from continuing operations before gains on sale and discontinued operations (usd per share)	$ (0.26)	$ 0.51	$ 1.50
Purchase price fair value adjustment (usd per share)	0.00	0.39	0.68
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (usd per share)	0.42	0.15	1.24
Net income from discontinued operations (usd per share)	0.00	0.00	0.19
Gain on sale of discontinued operations (usd per share)	0.00	0.14	1.64
Gain on sale of real estate (in dollars per share)	2.29	1.71	0.00
Depreciable real estate reserves (in dollars per share)	(0.10)	(0.19)	0.00
Net income attributable to SLGOP common unitholders (usd per share)	2.35	2.71	5.25
Diluted earnings per share:
Income from continuing operations before gains on sale and discontinued operations (usd per share)	(0.25)	0.51	1.52
Purchase price fair value adjustment (usd per share)	0.00	0.39	0.65
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (usd per share)	0.42	0.15	1.24
Net income from discontinued operations (usd per share)	0.00	0.00	0.19
Gain on sale of discontinued operations (usd per share)	0.00	0.14	1.63
Gain on sale of real estate (in dollars per share)	2.27	1.70	0.00
Depreciable real estate reserves (in dollars per share)	(0.10)	(0.19)	0.00
Net income attributable to SLGOP common unitholders (usd per share)	$ 2.34	$ 2.70	$ 5.23
Basic weighted average common units outstanding (in shares)	104,508	103,244	99,288
Diluted weighted average common units and common unit equivalents outstanding (in shares)	104,881	103,734	99,696