Consolidated Statement of Capital - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Increase (Decrease) in Partner's Capital
Acquisition of subsidiary interest from noncontrolling interest	$ (20,650)
Conversion of common units	55,697	$ 31,653	$ 17,287
DRSPP proceeds	99,555	64	67
Redemption of preferred units			(192,500)
Preferred units issuance costs			(33)
Reallocation of capital account relating to sale	(10,143)
Reallocation of noncontrolling interests in the operating partnership	20,915	(168,439)	(45,618)
Deferred compensation plan and stock award, net	(2,982)	(1,514)	166
Amortization of deferred compensation plan	26,721	29,749	26,329
Consolidation of Joint Venture Interest	35,178	30,800	8,164
Contributions-treasury shares			7,120
Cash distributions to noncontrolling interests	$ (119,784)	$ (7,019)	(14,623)
Preferred Units | Series C Preferred Stock
Increase (Decrease) in Partner's Capital
Redemption of preferred units			(180,340)
Preferred Units | Series I Preferred Stock
Increase (Decrease) in Partner's Capital
Preferred units issuance costs			$ (33)
Common Stock
Increase (Decrease) in Partner's Capital
DRSPP (in units)	776
DRSPP proceeds	$ 8
Deferred compensation plan and stock award, net, as adjusted (in units)	168	15	135
Deferred compensation plan and stock award, net	$ 2		$ 3
Contributions - net proceeds from common stock offering (in units)	1,007	1,654	3,062
Contributions-treasury shares (in units)			83
Contributions - proceeds from stock options exercised (in units)	217	348	224
Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Acquisition of subsidiary interest from noncontrolling interest	$ (11,084)
Reallocation of capital account relating to sale	(10,143)
Consolidation of Joint Venture Interest	35,178	$ 30,800	$ 8,164
Cash distributions to noncontrolling interests	(119,784)	(7,019)	(14,623)
SL Green Operating Partnership
Increase (Decrease) in Partner's Capital
Beginning Balance	7,459,216	7,016,876	6,907,103
Net income	299,927	524,646	146,000
Acquisition of subsidiary interest from noncontrolling interest	(20,650)
Other comprehensive income (loss)	(1,769)	8,231	14,376
Preferred distributions	(14,952)	(14,952)	(21,881)
Conversion of common units	55,697	31,653	17,287
DRSPP proceeds	99,555	64	67
Redemption of preferred units			(192,500)
Preferred units issuance costs			(33)
Reallocation of capital account relating to sale	(10,143)
Reallocation of noncontrolling interests in the operating partnership	20,915	(168,439)	(45,618)
Deferred compensation plan and stock award, net	(2,982)	(1,514)	166
Amortization of deferred compensation plan	26,721	29,749	26,329
Consolidation of Joint Venture Interest			8,164
Contribution to consolidated joint venture interests	35,178	30,800
Contributions - net proceeds from common stock offering	126,989	185,321	290,699
Contributions-treasury shares			7,120
Contributions - proceeds from stock options exercised	16,362	25,211	12,904
Cash distributions to noncontrolling interests	(119,784)	(7,019)	(14,623)
Cash distributions declared ($2.52, $2.10, and $1.49 per common unit, respectively, none of which represented a return of capital for federal income tax purposes)	(250,963)	(201,411)	(138,684)
Ending Balance	7,719,317	7,459,216	7,016,876
SL Green Operating Partnership | Preferred Units | Series C Preferred Stock
Increase (Decrease) in Partner's Capital
Beginning Balance	0	0	180,340
Redemption of preferred units			(180,340)
Ending Balance	0	0	0
SL Green Operating Partnership | Preferred Units | Series I Preferred Stock
Increase (Decrease) in Partner's Capital
Beginning Balance	221,932	221,932	221,965
Preferred units issuance costs			(33)
Ending Balance	$ 221,932	221,932	221,932
SL Green Operating Partnership | Common Stock
Increase (Decrease) in Partner's Capital
Issuance of common units (in units)	483
Conversion of common units	$ 55,697
SL Green Operating Partnership | Common Stock | Partners' Interest
Increase (Decrease) in Partner's Capital
Beginning Balance	$ 6,722,422	$ 6,318,684	$ 6,047,084
Beginning Balance (units)	97,325	94,993	91,250
Net income	$ 284,084	$ 518,056	$ 135,371
Acquisition of subsidiary interest from noncontrolling interest	(9,566)
Preferred distributions	$ (14,952)	$ (14,952)	$ (21,881)
Issuance of common units (in units)		315	239
Conversion of common units		$ 31,653	$ 17,287
DRSPP (in units)	776
DRSPP proceeds	$ 99,555	64	67
Redemption of preferred units			(12,160)
Reallocation of noncontrolling interests in the operating partnership	$ 20,915	$ (168,439)	$ (45,618)
Deferred compensation plan and stock award, net, as adjusted (in units)	168	15	135
Deferred compensation plan and stock award, net	$ (2,982)	$ (1,514)	$ 166
Amortization of deferred compensation plan	$ 26,721	$ 29,749	$ 26,329
Contributions - net proceeds from common stock offering (in units)	1,007	1,654	3,062
Contributions - net proceeds from common stock offering	$ 126,989	$ 185,321	$ 290,699
Contributions-treasury shares (in units)			83
Contributions-treasury shares			$ 7,120
Contributions - proceeds from stock options exercised (in units)	217	348	224
Contributions - proceeds from stock options exercised	$ 16,362	$ 25,211	$ 12,904
Cash distributions declared ($2.52, $2.10, and $1.49 per common unit, respectively, none of which represented a return of capital for federal income tax purposes)	(250,963)	(201,411)	(138,684)
Ending Balance	$ 7,074,282	$ 6,722,422	$ 6,318,684
Ending Balance (units)	99,976	97,325	94,993
SL Green Operating Partnership | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Partner's Capital
Beginning Balance	$ (6,980)	$ (15,211)	$ (29,587)
Other comprehensive income (loss)	(1,769)	8,231	14,376
Ending Balance	(8,749)	(6,980)	(15,211)
SL Green Operating Partnership | Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Beginning Balance	521,842	491,471	487,301
Net income	15,843	6,590	10,629
Acquisition of subsidiary interest from noncontrolling interest	(11,084)
Reallocation of capital account relating to sale	(10,143)
Consolidation of Joint Venture Interest			8,164
Contribution to consolidated joint venture interests	35,178	30,800
Cash distributions to noncontrolling interests	(119,784)	(7,019)	(14,623)
Ending Balance	$ 431,852	$ 521,842	$ 491,471