Consolidated Statements of Income (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenues
Rental revenue, net	$ 272,079,000	$ 261,675,000
Escalation and reimbursement	40,383,000	39,804,000
Investment income	54,084,000	52,708,000
Other income	14,582,000	5,766,000
Total revenues	381,128,000	359,953,000
Expenses
Operating expenses, including $3,411 (2014) and $3,889 (2013) of related party expenses	73,486,000	71,170,000
Real estate taxes	55,316,000	52,444,000
Ground rent	8,033,000	8,128,000
Interest expense, net of interest income	80,180,000	80,775,000
Amortization of deferred financing costs	3,868,000	4,463,000
Depreciation and amortization	89,379,000	78,623,000
Transaction related costs, net of recoveries	2,474,000	1,358,000
Marketing, general and administrative	23,257,000	21,067,000
Total expenses	335,993,000	318,028,000
Income from continuing operations before equity in net income from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture/real estate, loss on sale of investment in marketable securities and gain (loss) on early extinguishment of debt	45,135,000	41,925,000
Equity in net income from unconsolidated joint ventures	6,128,000	5,073,000
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	104,640,000	0
Loss on sale of investment in marketable securities	0	(57,000)
Gain (loss) on early extinguishment of debt	3,000	(18,513,000)
Income from continuing operations	155,906,000	28,428,000
Net income from discontinued operations	706,000	796,000
Gain on sale of discontinued operations	0	1,113,000
Net income	156,612,000	30,337,000
Net income attributable to noncontrolling interests:
Noncontrolling interests in the Operating Partnership	(4,729,000)	(555,000)
Noncontrolling interests in other partnerships	(1,490,000)	(2,901,000)
Preferred units distribution	(565,000)	(565,000)
Net income attributable to SL Green	149,828,000	26,316,000
Perpetual preferred stock dividends	(3,738,000)	(7,407,000)
Net income	146,090,000	18,909,000
Amounts attributable to SL Green common stockholders:
Income from continuing operations	44,047,000	17,055,000
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	101,359,000	0
Net income from discontinued operations	684,000	773,000
Gain on sale of discontinued operations	0	1,081,000
Net income	146,090,000	18,909,000
Basic earnings per share:
Income from continuing operations before discontinued operations (usd per share)	$ 0.46	$ 0.19
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (usd per share)	$ 1.07	$ 0.00
Net income from discontinued operations (usd per share)	$ 0.01	$ 0.01
Gain on sale of discontinued operations (usd per share)	$ 0.00	$ 0.01
Net income attributable to SL Green common stockholders (usd per share)	$ 1.54	$ 0.21
Diluted earnings per share:
Income from continuing operations before discontinued operations (usd per share)	$ 0.46	$ 0.19
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (usd per share)	$ 1.06	$ 0.00
Net income from discontinued operations (usd per share)	$ 0.01	$ 0.01
Gain on sale of discontinued operations (usd per share)	$ 0.00	$ 0.01
Net income attributable to SL Green common stockholders (usd per share)	$ 1.53	$ 0.21
Dividends per share (usd per share)	$ 0.50	$ 0.33
Basic weighted average common shares outstanding (in shares)	95,117	91,399
Diluted weighted average common shares and common share equivalents outstanding (usd per share)	98,716	94,302
SL Green Operating Partnership
Revenues
Rental revenue, net	272,079,000	261,675,000
Escalation and reimbursement	40,383,000	39,804,000
Investment income	54,084,000	52,708,000
Other income	14,582,000	5,766,000
Total revenues	381,128,000	359,953,000
Expenses
Operating expenses, including $3,411 (2014) and $3,889 (2013) of related party expenses	73,486,000	71,170,000
Real estate taxes	55,316,000	52,444,000
Ground rent	8,033,000	8,128,000
Interest expense, net of interest income	80,180,000	80,775,000
Amortization of deferred financing costs	3,868,000	4,463,000
Depreciation and amortization	89,379,000	78,623,000
Transaction related costs, net of recoveries	2,474,000	1,358,000
Marketing, general and administrative	23,257,000	21,067,000
Total expenses	335,993,000	318,028,000
Income from continuing operations before equity in net income from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture/real estate, loss on sale of investment in marketable securities and gain (loss) on early extinguishment of debt	45,135,000	41,925,000
Equity in net income from unconsolidated joint ventures	6,128,000	5,073,000
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	104,640,000	0
Loss on sale of investment in marketable securities	0	(57,000)
Gain (loss) on early extinguishment of debt	3,000	(18,513,000)
Income from continuing operations	155,906,000	28,428,000
Net income from discontinued operations	706,000	796,000
Gain on sale of discontinued operations	0	1,113,000
Net income	156,612,000	30,337,000
Net income attributable to noncontrolling interests:
Noncontrolling interests in other partnerships	(1,490,000)	(2,901,000)
Net income attributable to SL Green	154,557,000	26,871,000
Net income	150,819,000	19,464,000
Amounts attributable to SL Green common stockholders:
Income from continuing operations	45,473,000	17,555,000
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	104,640,000	0
Gain on sale of discontinued operations	0	1,113,000
Net income	150,819,000	19,464,000
Basic earnings per share:
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (usd per share)	$ 1.07	$ 0.00
Gain on sale of discontinued operations (usd per share)	$ 0.00	$ 0.01
Diluted earnings per share:
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (usd per share)	$ 1.06	$ 0.00
Gain on sale of discontinued operations (usd per share)	$ 0.00	$ 0.01
Dividends per share (usd per share)	$ 0.50
Noncontrolling Interest [Abstract]
Preferred unit distributions	(565,000)	(565,000)
Perpetual preferred unit distributions	(3,738,000)	(7,407,000)
Net income attributable to SLGOP common unitholders	150,819,000	19,464,000
Net income from discontinued operations	$ 706,000	$ 796,000
Net income from continuing operations before gains on sale and discontinued operations (in dollars per share)	$ 0.46	$ 0.19
Net income from discontinued operations (in dollars per share)	$ 0.01	$ 0.01
Net income attributable to SL Green common stockholders (in dollars per share)	$ 1.54	$ 0.21
Net income from continuing operations before gains on sale and discontinued operations (in dollars per share)	$ 0.46	$ 0.19
Net income from discontinued operations (in dollars per share)	$ 0.01	$ 0.01
Net income attributable to SL Green common stockholders (in dollars per share)	$ 1.53	$ 0.21
Dividends per unit (usd per share)	$ 0.5	$ 0.33
Basic weighted average common shares outstanding (in shares)	98,196	94,086
Diluted weighted average common shares and common share equivalents outstanding (in shares)	98,716	94,302