Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reconciliation of income from continuing operations to net income attributable to SL Green common stockholders
Income from continuing operations before purchase price fair value adjustment and equity in net gain (loss) on sale of interest in unconsolidated joint venture/real estate	$ 27,556	$ 24,468	$ 130,821	$ 78,412
Equity in net gain (loss) on sale of interest in unconsolidated joint venture/real estate	16,496	(354)	122,580	(3,937)
Purchase price fair value adjustment	(4,000)	0	67,446	(2,305)
Income from continuing operations	40,052	24,114	320,847	72,170
Net income from discontinued operations	4,035	7,435	15,449	19,851
Gain on sale of discontinued operations	29,507	13,787	144,242	14,900
Net income	$ 73,594	$ 45,336	$ 480,538	$ 106,921