Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
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 unconsolidated joint venture / partial interest and purchase price fair value adjustments	$ 108,923	$ 26,324	$ 130,271	$ 104,554
Purchase price fair value adjustment		475,102		488,890
Equity in net gain on sale of interest in unconsolidated joint venture/ real estate	9,534		16,794
Income from continuing operations	118,457	501,426	147,065	593,444
Net income (loss) from discontinued operations		1,676	(78)	3,549
Gain on sale of discontinued operations		46,085	6,627	46,085
Net income	118,457	549,187	153,614	643,078
Net income attributable to noncontrolling interests in the operating partnership	(3,421)	(11,925)	(4,309)	(13,776)
Net income attributable to noncontrolling interests in other partnerships	(3,887)	(3,259)	(4,958)	(6,869)
Preferred units distributions	(565)		(962)
Net income attributable to SL Green	110,584	534,003	143,385	622,433
Preferred stock dividends	(7,544)	(7,545)	(15,089)	(15,089)
Net income attributable to SL Green common stockholders	$ 103,040	$ 526,458	$ 128,296	$ 607,344