Consolidated Statements of Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-In-Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Noncontrolling Interests	Comprehensive Income	Series C Preferred Stock	Series D Preferred Stock
Balance at Dec. 31, 2008	$ 4,481,960	$ 604	$ 3,079,159	$ (302,705)	$ (54,747)	$ 979,939	$ 531,408		$ 151,981	$ 96,321
Balance (in shares) at Dec. 31, 2008		57,044,000
Comprehensive Income:
Net income	70,444					57,544	12,900	70,444
Net unrealized gain (loss) on derivative instruments	20,359				20,359			20,359
SL Green's share of joint venture net unrealized gain (loss) on derivative instruments	(233)				(233)			(233)
Unrealized Gain (loss) on marketable securities	1,083				1,083			1,083
Preferred dividends	(19,875)					(19,875)
Redemption of units and DRIP proceeds	28,567	7	28,560
Redemption of units and DRIP proceeds (in shares)		653,000
Reallocation of noncontrolling interest in the operating partnership	(23,217)					(23,217)
Deferred compensation plan & stock award, net	583	2	581
Deferred compensation plan & stock award, net (in shares)		246,000
Amortization of deferred compensation plan	30,040		30,040
Proceeds from issuance of common stock	387,138	196	386,942
Proceeds from issuance of common stock (in shares)		19,550,000
Proceeds from stock options exercised	619		619
Proceeds from stock options exercised (in shares)		22,000
Cash distributions to noncontrolling interests	(19,617)						(19,617)
Cash distribution declared ($0.55, $0.40 and $0.675 per common share, none of which represented a return of capital for federal income tax purposes for the year ended December 31, 2011, 2010 and 2009, respectively)	(44,722)					(44,722)
Comprehensive income								91,653
Balance at Dec. 31, 2009	4,913,129	809	3,525,901	(302,705)	(33,538)	949,669	524,691		151,981	96,321
Balance (in shares) at Dec. 31, 2009		77,515,000
Comprehensive Income:
Net income	314,582					300,575	14,007	314,582
Net unrealized gain (loss) on derivative instruments	(3,039)				(3,039)			(3,039)
SL Green's share of joint venture net unrealized gain (loss) on derivative instruments	571				571			571
Unrealized Gain (loss) on marketable securities	13,347				13,347			13,347
Preferred dividends	(29,749)					(29,749)
Redemption of units and DRIP proceeds	23,344	5	23,339
Redemption of units and DRIP proceeds (in shares)		470,000
Reallocation of noncontrolling interest in the operating partnership	(18,948)					(18,948)
Deferred compensation plan & stock award, net	20	2	535	(517)
Deferred compensation plan & stock award, net (in shares)		212,000
Amortization of deferred compensation plan	31,741		31,741
Deconsolidation of real estate investments	(6,521)					3,011	(9,532)
Equity component of convertible notes	76,039		76,039
Net proceeds from preferred stock offering	122,041								122,041
Proceeds from stock options exercised	3,288	1	3,287
Proceeds from stock options exercised (in shares)		110,000
Cash contributions from noncontrolling interests	2,788						2,788
Cash distributions to noncontrolling interests	(13,494)						(13,494)
Cash distribution declared ($0.55, $0.40 and $0.675 per common share, none of which represented a return of capital for federal income tax purposes for the year ended December 31, 2011, 2010 and 2009, respectively)	(31,595)					(31,595)
Comprehensive income								325,461
Balance at Dec. 31, 2010	5,397,544	817	3,660,842	(303,222)	(22,659)	1,172,963	518,460		274,022	96,321
Balance (in shares) at Dec. 31, 2010	78,307,000	78,307,000
Comprehensive Income:
Net income	662,493					647,410	15,083	662,493
Net unrealized gain (loss) on derivative instruments	(3,501)				(3,501)			(3,501)
SL Green's share of joint venture net unrealized gain (loss) on derivative instruments	902				902			902
Unrealized Gain (loss) on marketable securities	(3,187)				(3,187)			(3,187)
Preferred dividends	(30,178)					(30,178)
Redemption of units and DRIP proceeds	898		898
Redemption of units and DRIP proceeds (in shares)		13,000
Reallocation of noncontrolling interest in the operating partnership	(39,040)					(39,040)
Deferred compensation plan & stock award, net	(4,787)	3	696	(5,486)
Deferred compensation plan & stock award, net (in shares)		262,000
Amortization of deferred compensation plan	33,252		33,252
Proceeds from issuance of common stock	531,306	70	531,236
Proceeds from issuance of common stock (in shares)		6,957,000
Proceeds from stock options exercised	10,037	2	10,035
Proceeds from stock options exercised (in shares)		244,000
Consolidation of joint venture interest	87,798						87,798
Cash distributions to noncontrolling interests	(143,579)						(143,579)
Cash distribution declared ($0.55, $0.40 and $0.675 per common share, none of which represented a return of capital for federal income tax purposes for the year ended December 31, 2011, 2010 and 2009, respectively)	(46,649)					(46,649)
Comprehensive income								656,707
Balance at Dec. 31, 2011	$ 6,453,309	$ 892	$ 4,236,959	$ (308,708)	$ (28,445)	$ 1,704,506	$ 477,762		$ 274,022	$ 96,321
Balance (in shares) at Dec. 31, 2011	85,783,000	85,783,000