Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
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	$ 51,266	$ 28,428
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	104,640	0
Income from continuing operations	155,906	28,428
Net income from discontinued operations	706	796
Gain on sale of discontinued operations	0	1,113
Net income	$ 156,612	$ 30,337