Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Commercial real estate properties, at cost:
Land and land interests	$ 3,032,526	$ 2,886,099
Building and improvements	7,884,663	7,389,766
Building leasehold and improvements	1,366,281	1,346,748
Properties under capital lease	50,310	40,340
Total commercial real estate properties, at cost	12,333,780	11,662,953
Less: accumulated depreciation	(1,646,240)	(1,393,323)
Total commercial real estate properties, net	10,687,540	10,269,630
Assets held for sale	0	4,901
Cash and cash equivalents	206,692	189,984
Restricted cash	142,051	136,071
Investment in marketable securities	32,049	21,429
Tenant and other receivables, net of allowance of $17,325 and $14,341 in 2013 and 2012, respectively	60,393	55,855
Related party receivables	8,530	7,531
Deferred rents receivable, net of allowance of $30,333 and $29,580 in 2013 and 2012, respectively	386,508	340,747
Debt and preferred equity investments, net of discounts and deferred origination fees of $18,593 and $22,341 in 2013 and 2012, and allowance of $1,000 and $7,000 in 2013 and 2012, respectively	1,304,839	1,348,434
Investments in unconsolidated joint ventures	1,113,218	1,032,243
Deferred costs, net	267,058	261,145
Other assets	750,123	718,326
Total assets	14,959,001	14,386,296
Liabilities
Mortgages and other loans payable	4,860,578	4,615,464
Revolving credit facility	220,000	70,000
Term loan and senior unsecured notes	1,739,330	1,734,956
Accrued interest payable and other liabilities	114,622	81,080
Accounts payable and accrued expenses	145,889	159,598
Deferred revenue	263,261	312,995
Capitalized lease obligations	47,671	37,518
Deferred land leases payable	22,185	20,897
Dividend and distributions payable	52,255	37,839
Security deposits	61,308	46,253
Liabilities related to assets held for sale	0	136
Junior subordinate deferrable interest debentures held by trusts that issued trust preferred securities	100,000	100,000
Total liabilities	7,627,099	7,216,736
Commitments and contingencies	0	0
Noncontrolling interests in Operating Partnership	265,476	212,907
Equity
Common stock, $0.01 par value, 160,000 shares authorized and 98,563 and 94,896 issued and outstanding at December 31, 2013 and 2012, respectively (including 3,570 and 3,646 shares held in Treasury at December 31, 2013 and 2012, respectively)	986	950
Additional paid-in-capital	5,015,904	4,667,900
Treasury stock at cost	(317,356)	(322,858)
Accumulated other comprehensive loss	(15,211)	(29,587)
Retained earnings	1,619,150	1,701,092
Total SL Green stockholders' equity	6,525,405	6,419,802
Noncontrolling interests in other partnerships	491,471	487,301
Total equity	7,016,876	6,907,103
Total liabilities and equity	14,959,001	14,386,296
Series G Preferred Units
Liabilities
Preferred Units	47,550	47,550
Series H Preferred Units
Liabilities
Preferred Units	2,000	2,000
Series C Preferred Stock
Equity
Preferred stock, issued	0	180,340
Series I Preferred Stock
Equity
Preferred stock, issued	221,932	221,965
SL Green Operating Partnership
Commercial real estate properties, at cost:
Land and land interests	3,032,526	2,886,099
Building and improvements	7,884,663	7,389,766
Building leasehold and improvements	1,366,281	1,346,748
Properties under capital lease	50,310	40,340
Total commercial real estate properties, at cost	12,333,780	11,662,953
Less: accumulated depreciation	(1,646,240)	(1,393,323)
Total commercial real estate properties, net	10,687,540	10,269,630
Assets held for sale	0	4,901
Cash and cash equivalents	206,692	189,984
Restricted cash	142,051	136,071
Investment in marketable securities	32,049	21,429
Tenant and other receivables, net of allowance of $17,325 and $14,341 in 2013 and 2012, respectively	60,393	55,855
Related party receivables	8,530	7,531
Deferred rents receivable, net of allowance of $30,333 and $29,580 in 2013 and 2012, respectively	386,508	340,747
Debt and preferred equity investments, net of discounts and deferred origination fees of $18,593 and $22,341 in 2013 and 2012, and allowance of $1,000 and $7,000 in 2013 and 2012, respectively	1,304,839	1,348,434
Investments in unconsolidated joint ventures	1,113,218	1,032,243
Deferred costs, net	267,058	261,145
Other assets	750,123	718,326
Total assets	14,959,001	14,386,296
Liabilities
Mortgages and other loans payable	4,860,578	4,615,464
Revolving credit facility	220,000	70,000
Term loan and senior unsecured notes	1,739,330	1,734,956
Accrued interest payable and other liabilities	114,622	81,080
Accounts payable and accrued expenses	145,889	159,598
Deferred revenue	263,261	312,995
Capitalized lease obligations	47,671	37,518
Deferred land leases payable	22,185	20,897
Dividend and distributions payable	52,255	37,839
Security deposits	61,308	46,253
Liabilities related to assets held for sale	0	136
Junior subordinate deferrable interest debentures held by trusts that issued trust preferred securities	100,000	100,000
Total liabilities	7,627,099	7,216,736
Commitments and contingencies	0	0
Equity
Accumulated other comprehensive loss	(15,662)	(30,649)
Total liabilities and equity	14,959,001	14,386,296
SL Green stockholders equity:
SL Green partners' capital (979 and 940 general partner common units and 94,014 and 90,310 limited partner common units outstanding at December 31, 2013 and 2012, respectively)	6,506,747	6,189,529
Limited partner interests in SLGOP (2,902 and 2,760 limited partner common units outstanding at December 31, 2013 and 2012, respectively	77,864	71,524
Total SLGOP partners' capital	6,790,881	6,632,709
Noncontrolling interests in other partnerships	491,471	487,301
Total capital	7,282,352	7,120,010
SL Green Operating Partnership | Series G Preferred Units
SL Green stockholders equity:
Preferred units	47,550	47,550
SL Green Operating Partnership | Series H Preferred Units
SL Green stockholders equity:
Preferred units	2,000	2,000
SL Green Operating Partnership | Series C Preferred Stock
SL Green stockholders equity:
Preferred units	0	180,340
Total capital	0	180,340
SL Green Operating Partnership | Series I Preferred Stock
SL Green stockholders equity:
Preferred units	221,932	221,965
Total capital	$ 221,932	$ 221,965