Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 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	$ 29,256	$ 21,431
Equity in net gain on sale of interest in unconsolidated joint venture/real estate		7,260
Income from continuing operations	29,256	28,691
Net loss from discontinued operations	(32)	(161)
Gain on sale of discontinued operations	1,113	6,627
Net income	30,337	35,157
Net income attributable to noncontrolling interests in operating partnership	(555)	(888)
Net income attributable to noncontrolling interests in other partnerships	(2,901)	(1,071)
Preferred unit distributions	(565)	(397)
Net income attributable to SL Green	26,316	32,801
Perpetual preferred stock dividends	(7,407)	(7,545)
Net income attributable to SL Green common stockholders	$ 18,909	$ 25,256