Consolidated Statements of Capital Statement (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014
Increase (Decrease) in Stockholders' Equity
Other comprehensive income	$ 3,413	$ 12,662
DRIP proceeds		40
Redemption of units		26,392
Deferred compensation plan and stock award, net		(1,363)
Amortization of deferred compensation plan		23,822
Contributions to consolidated joint venture interests		28,058
Cash distributions to noncontrolling interests		(5,745)
Common Stock
Increase (Decrease) in Stockholders' Equity
Redemption of units		3
Redemption of units (in units)		264
Deferred compensation plan and stock award, net		0
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Contributions to consolidated joint venture interests		28,058
Cash distributions to noncontrolling interests		(5,745)
SL Green Operating Partnership
Increase (Decrease) in Stockholders' Equity
Beginning Balance		7,282,352
Net income		478,588
Other comprehensive income	3,413	12,662
Preferred distributions		(11,214)
Issuance of common units		22,862
DRIP proceeds		40
Redemption of units		0
Deferred compensation plan and stock award, net		(1,363)
Amortization of deferred compensation plan		23,822
Contributions to consolidated joint venture interests		28,058
Contributions—net proceeds from common stock offering		42,698
Contributions—proceeds from stock options exercised		20,509
Cash distributions to noncontrolling interests		(5,745)
Cash distribution declared ($1.50 per common unit, none of which represented a return of capital for federal income tax purposes)		(148,542)
Ending Balance	7,744,727	7,744,727
SL Green Operating Partnership | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity
Beginning Balance		(15,662)
Other comprehensive income		12,662
Ending Balance	(3,000)	(3,000)
SL Green Operating Partnership | Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Beginning Balance		491,471
Net income		5,045
Contributions to consolidated joint venture interests		28,058
Cash distributions to noncontrolling interests		(5,745)
Ending Balance	518,829	518,829
SL Green Operating Partnership | General Partner
Increase (Decrease) in Stockholders' Equity
Beginning Balance		6,506,747
Balance (shares)		94,993
Net income		446,319
DRIP proceeds		40
DRIP proceeds (in units)		0
Redemption of units		26,392
Redemption of units (in units)		264
Deferred compensation plan and stock award, net		(1,363)
Deferred compensation plan and stock award, net (in units)		4
Amortization of deferred compensation plan		23,822
Contributions—net proceeds from common stock offering		42,698
Contributions—net proceeds from common stock offering (in units)		394
Contributions—proceeds from stock options exercised		20,509
Contributions—proceeds from stock options exercised (in units)		290
Cash distribution declared ($1.50 per common unit, none of which represented a return of capital for federal income tax purposes)		(143,060)
Ending Balance	6,922,104	6,922,104
Balance (shares)	95,945	95,945
SL Green Operating Partnership | Limited Partners
Increase (Decrease) in Stockholders' Equity
Balance (shares)		2,902
Issuance of common units (in units)		1,097
Redemption of units (in units)		(264)
Deferred compensation plan and stock award, net (in units)
Balance (shares)	3,735	3,735
SL Green Operating Partnership | Limited Partners | Common Stock
Increase (Decrease) in Stockholders' Equity
Beginning Balance		77,864
Net income		16,010
Issuance of common units		22,862
Redemption of units		(26,392)
Cash distribution declared ($1.50 per common unit, none of which represented a return of capital for federal income tax purposes)		(5,482)
Ending Balance	84,862	84,862
SL Green Operating Partnership | Series I Preferred Stock
Increase (Decrease) in Stockholders' Equity
Beginning Balance		221,932
Net income		11,214
Preferred distributions		(11,214)
Ending Balance	$ 221,932	$ 221,932