Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Commercial real estate properties, at cost:
Land and land interests	$ 3,112,013	$ 3,032,526
Building and improvements	7,767,616	7,884,663
Building leasehold and improvements	1,375,007	1,366,281
Properties under capital lease	27,445	50,310
Total commercial real estate properties, at cost	12,282,081	12,333,780
Less: accumulated depreciation	(1,695,568)	(1,646,240)
Total commercial real estate properties, net	10,586,513	10,687,540
Assets held for sale	63,925	0
Cash and cash equivalents	447,162	206,692
Restricted cash	154,492	142,051
Investment in marketable securities	32,130	32,049
Tenant and other receivables, net of allowance of $18,627 and $17,325 in 2014 and 2013, respectively	47,296	60,393
Related party receivables	19,947	8,530
Deferred rents receivable, net of allowance of $27,939 and $30,333 in 2014 and 2013, respectively	378,980	386,508
Debt and preferred equity investments, net of discounts and deferred origination fees of $17,751 and $18,593 in 2014 and 2013, respectively, and allowance of $1,000 in 2013	1,493,725	1,304,839
Investments in unconsolidated joint ventures	1,061,704	1,113,218
Deferred costs, net	261,542	267,058
Other assets	815,873	750,123
Total assets	15,363,289	14,959,001
Liabilities
Mortgages and other loans payable	4,971,022	4,860,578
Revolving credit facility	0	220,000
Term loan and senior unsecured notes	2,124,397	1,739,330
Accrued interest payable and other liabilities	112,852	114,622
Accounts payable and accrued expenses	140,346	145,889
Deferred revenue	259,929	263,261
Capitalized lease obligations	20,541	47,671
Deferred land leases payable	958	22,185
Dividend and distributions payable	52,471	52,255
Security deposits	65,077	61,308
Liabilities related to assets held for sale	49,704	0
Junior subordinate deferrable interest debentures held by trusts that issued trust preferred securities	100,000	100,000
Total liabilities	7,897,297	7,627,099
Commitments and contingencies	0	0
Noncontrolling interests in Operating Partnership	298,858	265,476
Equity
Common stock, $0.01 par value, 160,000 shares authorized and 98,919 and 98,563 issued and outstanding at March 31, 2014 and December 31, 2013, respectively (including 3,600 and 3,570 shares held in Treasury at March 31, 2014 and December 31, 2013, respectively)	990	986
Additional paid-in-capital	5,049,507	5,015,904
Treasury stock at cost	(320,076)	(317,356)
Accumulated other comprehensive loss	(14,872)	(15,211)
Retained earnings	1,688,211	1,619,150
Total SL Green stockholders' equity	6,625,692	6,525,405
Noncontrolling interests in other partnerships	491,892	491,471
Total equity	7,117,584	7,016,876
Total liabilities and equity	15,363,289	14,959,001
Series G Preferred Units
Liabilities
Preferred Units	47,550	47,550
Series H Preferred Units
Liabilities
Preferred Units	2,000	2,000
Series I Preferred Stock
Equity
Series I Preferred Stock, $0.01 par value, $25.00 liquidation preference, 9,200 issued and outstanding at both March 31, 2014 and December 31, 2013	221,932	221,932
SL Green Operating Partnership
Commercial real estate properties, at cost:
Land and land interests	3,112,013	3,032,526
Building and improvements	7,767,616	7,884,663
Building leasehold and improvements	1,375,007	1,366,281
Properties under capital lease	27,445	50,310
Total commercial real estate properties, at cost	12,282,081	12,333,780
Less: accumulated depreciation	(1,695,568)	(1,646,240)
Total commercial real estate properties, net	10,586,513	10,687,540
Assets held for sale	63,925	0
Cash and cash equivalents	447,162	206,692
Restricted cash	154,492	142,051
Investment in marketable securities	32,130	32,049
Tenant and other receivables, net of allowance of $18,627 and $17,325 in 2014 and 2013, respectively	47,296	60,393
Related party receivables	19,947	8,530
Deferred rents receivable, net of allowance of $27,939 and $30,333 in 2014 and 2013, respectively	378,980	386,508
Debt and preferred equity investments, net of discounts and deferred origination fees of $17,751 and $18,593 in 2014 and 2013, respectively, and allowance of $1,000 in 2013	1,493,725	1,304,839
Investments in unconsolidated joint ventures	1,061,704	1,113,218
Deferred costs, net	261,542	267,058
Other assets	815,873	750,123
Total assets	15,363,289	14,959,001
Liabilities
Mortgages and other loans payable	4,971,022	4,860,578
Revolving credit facility	0	220,000
Term loan and senior unsecured notes	2,124,397	1,739,330
Accrued interest payable and other liabilities	112,852	114,622
Accounts payable and accrued expenses	140,346	145,889
Deferred revenue	259,929	263,261
Capitalized lease obligations	20,541	47,671
Deferred land leases payable	958	22,185
Dividend and distributions payable	52,471	52,255
Security deposits	65,077	61,308
Liabilities related to assets held for sale	49,704	0
Junior subordinate deferrable interest debentures held by trusts that issued trust preferred securities	100,000	100,000
Total liabilities	7,897,297	7,627,099
Commitments and contingencies	0	0
Equity
Accumulated other comprehensive loss	(15,365)	(15,662)
Total liabilities and equity	15,363,289	14,959,001
SLGOP partners' capital:
SL Green partners' capital 984 and 979 general partner common units and 94,335 and 94,014 limited partner common units outstanding at March 31, 2014 and December 31, 2013, respectively)	6,636,159	6,506,747
Limited partner interests in SLGOP (3,000 and 2,902 limited partner common units outstanding at March 31, 2014 and December 31, 2013, respectively)	81,824	77,864
Total SLGOP partners' capital	6,924,550	6,790,881
Noncontrolling interests in other partnerships	491,892	491,471
Total capital	7,416,442	7,282,352
SL Green Operating Partnership | Series G Preferred Units
SLGOP partners' capital:
Preferred units	47,550	47,550
SL Green Operating Partnership | Series H Preferred Units
SLGOP partners' capital:
Preferred units	2,000	2,000
SL Green Operating Partnership | Series I Preferred Stock
SLGOP partners' capital:
Preferred units	221,932	221,932
Total capital	$ 221,932	$ 221,932