Consolidated Statements of Capital Statement (USD $) In Thousands, unless otherwise specified	12 Months Ended																		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 SL Green Operating Partnership	Dec. 31, 2012 SL Green Operating Partnership	Dec. 31, 2011 SL Green Operating Partnership	Dec. 31, 2013 SL Green Operating Partnership General Partner	Dec. 31, 2012 SL Green Operating Partnership General Partner	Dec. 31, 2011 SL Green Operating Partnership General Partner	Dec. 31, 2013 SL Green Operating Partnership Limited Partners	Dec. 31, 2012 SL Green Operating Partnership Limited Partners	Dec. 31, 2011 SL Green Operating Partnership Limited Partners	Dec. 31, 2013 SL Green Operating Partnership Series C Preferred Stock	Dec. 31, 2012 SL Green Operating Partnership Series C Preferred Stock	Dec. 31, 2011 SL Green Operating Partnership Series C Preferred Stock	Dec. 31, 2012 SL Green Operating Partnership Series D Preferred Stock	Dec. 31, 2011 SL Green Operating Partnership Series D Preferred Stock	Dec. 31, 2013 SL Green Operating Partnership Series D Preferred Stock	Dec. 31, 2013 SL Green Operating Partnership Series I Preferred Stock	Dec. 31, 2012 SL Green Operating Partnership Series I Preferred Stock	Dec. 31, 2013 SL Green Operating Partnership Common Stock Limited Partners	Dec. 31, 2012 SL Green Operating Partnership Common Stock Limited Partners	Dec. 31, 2011 SL Green Operating Partnership Common Stock Limited Partners	Dec. 31, 2013 SL Green Operating Partnership Accumulated Other Comprehensive Income (Loss)	Dec. 31, 2012 SL Green Operating Partnership Accumulated Other Comprehensive Income (Loss)	Dec. 31, 2011 SL Green Operating Partnership Accumulated Other Comprehensive Income (Loss)	Dec. 31, 2013 SL Green Operating Partnership Noncontrolling Interests	Dec. 31, 2012 SL Green Operating Partnership Noncontrolling Interests	Dec. 31, 2011 SL Green Operating Partnership Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Beginning Balance				$ 7,120,010	$ 6,648,339	$ 5,481,882	$ 6,189,529	$ 5,714,856	$ 4,573,565				$ 180,340	$ 274,022	$ 274,022	$ 96,321	$ 96,321	$ 0	$ 221,965	$ 0	$ 71,524	$ 114,497	$ 42,556	$ (30,649)	$ (29,119)	$ (23,042)	$ 487,301	$ 477,762	$ 518,460
Balance (shares)							91,250	85,783	78,307	2,760	2,765	1,249
Net income				149,023	207,593	677,122	113,490	165,994	617,232				6,932	20,290	22,300	4,266	7,878		14,949	5,855	3,023	5,597	14,629				10,629	5,591	15,083
Other comprehensive income	14,987	(1,530)	(6,077)	14,987	(1,530)	(6,077)																		14,987	(1,530)	(6,077)
Preferred distributions				(21,881)	(30,411)	(30,178)							(6,932)	(20,290)	(22,300)	(4,266)	(7,878)		(14,949)	(5,855)
Issuance of units in the Operating Partnership	24,750	42,239	62,443	24,750	42,239	60,443															24,750	42,239	60,443
Issuance of units (in units)										381	801	1,530
DRIP proceeds	67	99,570	898	67	99,570	32	67	99,570	898														(866)
DRIP proceeds (in units)							0	(1,305)	(13)			(12)
Conversion of units	17,287	87,513		0	0		17,287	87,513													(17,287)	(87,513)
Conversion of units (in units)							(239)	(1,096)		239	1,096
Redemption of preferred units	(192,500)	(200,013)		(192,500)	(200,013)		(12,160)	(10,010)					(180,340)	(93,682)		(96,321)
Preferred units issuance costs	(33)			(33)															(33)
Deferred compensation plan (shares)							(135)	(43)	(262)		(290)	(2)
Deferred compensation plan	166	(13,428)	(4,787)	166	(13,428)	(4,787)	166	(13,428)	(4,787)
Amortization of deferred compensation plan	26,329	28,742	33,252	26,329	28,742	33,252	26,329	28,742	33,252
Contribution to consolidated joint venture interest				8,164																							8,164
Contributions to consolidated joint venture					25,894	86,797																	(1,001)					25,894	87,798
Contributions—net proceeds from preferred stock offering					221,965															221,965
Contributions—net proceeds from common stock offering				290,699	201,279	531,306	290,699	201,279	531,306
Contributions - net proceeds from common stock offering (in units)							3,062	2,640	6,957
Contributions-treasury shares	(7,120)			7,120			7,120
Contributions-treasury shares (shares)							83
Contributions - proceeds from stock options exercised				12,904	13,173	10,037	12,904	13,173	10,037
Contributions - proceeds from stock options exercised (in units)							224	383	244
Cash distributions to noncontrolling interests		(21,946)	(143,579)	(14,623)	(21,946)	(143,579)																					(14,623)	(21,946)	(143,579)
Cash distribution declared ($0.99 per common unit, none of which represented a return of capital for federal income tax purposes)				(142,830)	(101,456)	(47,911)	(138,684)	(98,160)	(46,647)												(4,146)	(3,296)	(1,264)
Ending Balance				$ 7,282,352	$ 7,120,010	$ 6,648,339	$ 6,506,747	$ 6,189,529	$ 5,714,856				$ 0	$ 180,340	$ 274,022	$ 0	$ 96,321	$ 0	$ 221,932	$ 221,965	$ 77,864	$ 71,524	$ 114,497	$ (15,662)	$ (30,649)	$ (29,119)	$ 491,471	$ 487,301	$ 477,762
Balance (shares)							94,993	91,250	85,783	2,902	2,760	2,765