Segment Information (Details 2) (USD $) In Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Reconciliation of income from continuing operations to net income attributable to SL Green common stockholders
Income from continuing operations	$ 502,542	$ 148,096	$ 595,695	$ 172,312
Net income from discontinued operations	560	2,403	1,298	4,320
Gain on sale of discontinued operations	46,085		46,085
Net income	549,187	150,499	643,078	176,632
Net income attributable to noncontrolling interests in the operating partnership	(11,925)	(2,467)	(13,776)	(2,758)	(4,574)
Net income attributable to noncontrolling interests in other partnerships	(3,259)	(3,449)	(6,869)	(7,097)
Net income attributable to SL Green	534,003	144,583	622,433	166,777
Preferred dividends	(7,545)	(7,545)	(15,089)	(14,660)
Net income attributable to SL Green common stockholders	$ 526,458	$ 137,038	$ 607,344	$ 152,117