Consolidated Statements of Cash Flows (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating Activities
Net income	$ 156,612,000	$ 30,337,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	93,680,000	85,146,000
Equity in net income from unconsolidated joint ventures	(6,128,000)	(5,073,000)
Distributions of cumulative earnings from unconsolidated joint ventures	7,669,000	6,901,000
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate	(104,640,000)	0
Gain on sale of discontinued operations	0	(1,113,000)
(Gain) loss on early extinguishment of debt	(3,000)	10,958,000
Deferred rents receivable	(11,133,000)	(13,923,000)
Other non-cash adjustments	(12,792,000)	(24,028,000)
Changes in operating assets and liabilities:
Restricted cash—operations	(10,520,000)	5,447,000
Tenant and other receivables	11,899,000	7,409,000
Related party receivables	(11,885,000)	(3,638,000)
Deferred lease costs	(4,476,000)	(4,646,000)
Other assets	(32,949,000)	(21,185,000)
Accounts payable, accrued expenses and other liabilities and security deposits	(1,821,000)	869,000
Deferred revenue and deferred land leases payable	14,635,000	16,095,000
Net cash provided by operating activities	88,148,000	89,556,000
Investing Activities
Acquisitions of real estate property	0	(48,500,000)
Additions to land, buildings and improvements	(48,213,000)	(11,617,000)
Escrowed cash—capital improvements/acquisition deposits	(34,861,000)	191,000
Investments in unconsolidated joint ventures	(18,966,000)	(49,996,000)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	72,558,000	5,333,000
Net proceeds from disposition of real estate/joint venture interest	109,196,000	5,852,000
Other investments	(1,573,000)	(10,146,000)
Origination of debt and preferred equity investments	(150,464,000)	(195,004,000)
Repayments or redemption of debt and preferred equity investments	522,000	134,811,000
Net cash used in investing activities	(71,801,000)	(169,076,000)
Financing Activities
Proceeds from mortgages and other loans payable	121,216,000	980,333,000
Repayments of mortgages and other loans payable	(10,772,000)	(780,332,000)
Proceeds from revolving credit facility, term loan and senior unsecured notes	603,000,000	155,000,000
Repayments of revolving credit facility, term loan and senior unsecured notes	(440,690,000)	(199,960,000)
Proceeds from stock options exercised and DRIP issuance	8,992,000	4,546,000
Net proceeds from sale of common stock	24,000	(24,000)
Net proceeds from sale of preferred stock	0	(33,000)
Distributions to noncontrolling interests in other partnerships	(1,586,000)	(4,879,000)
Contributions from noncontrolling interests in other partnerships	517,000	3,110,000
Distributions to noncontrolling interests in the Operating Partnership	(1,500,000)	(853,000)
Dividends paid on common and preferred stock	(51,652,000)	(38,591,000)
Deferred loan costs and capitalized lease obligation	(3,426,000)	(8,677,000)
Net cash provided by financing activities	224,123,000	109,640,000
Net increase in cash and cash equivalents	240,470,000	30,120,000
Cash and cash equivalents at beginning of period	206,692,000	189,984,000
Cash and cash equivalents at end of period	447,162,000	220,104,000
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of common stock as deferred compensation	1,295,000	0
Issuance of units in the Operating Partnership	17,314,000	777,000
Redemption of units in the Operating Partnership	16,583,000	17,287,000
Derivative instruments at fair value	110,000	128,000
Tenant improvements and capital expenditures payable	9,898,000	9,136,000
Fair value adjustment to noncontrolling interest in the Operating Partnership	29,464,000	24,016,000
Capital leased asset	0	6,839,000
Transfer to net assets held for sale	63,925,000	0
Transfer to liabilities related to net assets held for sale	49,704,000	0
Transfer of financing receivable to debt investment	19,675,000	0
SL Green Operating Partnership
Operating Activities
Net income	156,612,000	30,337,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	93,680,000	85,146,000
Equity in net income from unconsolidated joint ventures	(6,128,000)	(5,073,000)
Distributions of cumulative earnings from unconsolidated joint ventures	7,669,000	6,901,000
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate	(104,640,000)	0
Gain on sale of discontinued operations	0	(1,113,000)
(Gain) loss on early extinguishment of debt	(3,000)	10,958,000
Deferred rents receivable	(11,133,000)	(13,923,000)
Other non-cash adjustments	(12,792,000)	(24,028,000)
Changes in operating assets and liabilities:
Restricted cash—operations	(10,520,000)	5,447,000
Tenant and other receivables	11,899,000	7,409,000
Related party receivables	(11,885,000)	(3,638,000)
Deferred lease costs	(4,476,000)	(4,646,000)
Other assets	(32,949,000)	(21,185,000)
Accounts payable, accrued expenses and other liabilities and security deposits	(1,821,000)	869,000
Deferred revenue and deferred land leases payable	14,635,000	16,095,000
Net cash provided by operating activities	88,148,000	89,556,000
Investing Activities
Acquisitions of real estate property	0	(48,500,000)
Additions to land, buildings and improvements	(48,213,000)	(11,617,000)
Escrowed cash—capital improvements/acquisition deposits	(34,861,000)	191,000
Investments in unconsolidated joint ventures	(18,966,000)	(49,996,000)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	72,558,000	5,333,000
Net proceeds from disposition of real estate/joint venture interest	109,196,000	5,852,000
Other investments	(1,573,000)	(10,146,000)
Origination of debt and preferred equity investments	(150,464,000)	(195,004,000)
Repayments or redemption of debt and preferred equity investments	522,000	134,811,000
Net cash used in investing activities	(71,801,000)	(169,076,000)
Financing Activities
Proceeds from mortgages and other loans payable	121,216,000	980,333,000
Repayments of mortgages and other loans payable	(10,772,000)	(780,332,000)
Proceeds from revolving credit facility, term loan and senior unsecured notes	603,000,000	155,000,000
Repayments of revolving credit facility, term loan and senior unsecured notes	(440,690,000)	(199,960,000)
Proceeds from stock options exercised and DRIP issuance	8,992,000	4,546,000
Net proceeds from sale of common stock	24,000	(24,000)
Net proceeds from sale of preferred stock	0	(33,000)
Distributions to noncontrolling interests in other partnerships	(1,586,000)	(4,879,000)
Contributions from noncontrolling interests in other partnerships	517,000	3,110,000
Dividends paid on common and preferred stock	(53,152,000)	(39,444,000)
Deferred loan costs and capitalized lease obligation	(3,426,000)	(8,677,000)
Net cash provided by financing activities	224,123,000	109,640,000
Net increase in cash and cash equivalents	240,470,000	30,120,000
Cash and cash equivalents at beginning of period	206,692,000	189,984,000
Cash and cash equivalents at end of period	447,162,000	220,104,000
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of common stock as deferred compensation	1,295,000	0
Issuance of units in the Operating Partnership	17,314,000	777,000
Redemption of units in the Operating Partnership	16,583,000	17,287,000
Derivative instruments at fair value	110,000	128,000
Tenant improvements and capital expenditures payable	9,898,000	9,136,000
Capital leased asset	0	6,839,000
Transfer to net assets held for sale	63,925,000	0
Transfer to liabilities related to net assets held for sale	49,704,000	0
Transfer of financing receivable to debt investment	$ 19,675,000	$ 0