Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reconciliation of income from continuing operations to net income attributable to SL Green common stockholders
Income from continuing operations before equity in net gain on sale of interest in unconsolidated joint venture/real estate	$ 37,814	$ 108,024	$ 66,040	$ 128,262
Purchase price fair value adjustment	(2,305)		(2,305)
Equity in net (loss) gain on sale of interest in unconsolidated joint venture/real estate	(3,583)	9,534	(3,583)	16,794
Income from continuing operations	31,926	117,558	60,152	145,056
Net (loss) income from discontinued operations	(678)	899	320	1,931
Gain on sale of discontinued operations			1,113	6,627
Net income	31,248	118,457	61,585	153,614
Net income attributable to noncontrolling interests in the Operating Partnership	(244)	(3,421)	(799)	(4,309)
Net income attributable to noncontrolling interests in other partnerships	(3,004)	(3,887)	(5,905)	(4,958)
Preferred unit distributions	(565)	(565)	(1,130)	(962)
Net income attributable to SL Green	27,435	110,584	53,751	143,385
Preferred redemption costs	(12,160)		(12,160)
Perpetual preferred stock dividends	(6,999)	(7,544)	(14,406)	(15,089)
Net income attributable to SL Green common stockholders	$ 8,276	$ 103,040	$ 27,185	$ 128,296