Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Commercial real estate properties, at cost:
Land and land interests	$ 2,886,099	$ 2,684,626
Building and improvements	7,389,766	7,147,527
Building leasehold and improvements	1,346,748	1,302,790
Properties under capital lease	40,340	12,208
Commercial real estate properties, at cost	11,662,953	11,147,151
Less: accumulated depreciation	(1,393,323)	(1,136,603)
Commercial real estate properties, net	10,269,630	10,010,548
Assets held for sale	4,901	76,562
Cash and cash equivalents	189,984	138,192
Restricted cash	136,071	86,584
Investment in marketable securities	21,429	25,323
Tenant and other receivables, net of allowance of $21,652 and $16,772 in 2012 and 2011, respectively	48,544	32,107
Related party receivables	7,531	4,001
Deferred rents receivable, net of allowance of $29,580 and $29,156 in 2012 and 2011, respectively	340,747	281,974
Debt and preferred equity investments, net of discount of $13,572 and $24,996 and allowance of $7,000 and $50,175 in 2012 and 2011, respectively	1,357,203	985,942
Investments in unconsolidated joint ventures	1,032,243	893,933
Deferred costs, net	261,145	210,786
Other assets	718,326	737,900
Total assets	14,387,754	13,483,852
Liabilities
Mortgages and other loans payable	4,615,464	4,314,741
Revolving credit facility	70,000	350,000
Term loan and senior unsecured notes	1,734,956	1,270,656
Accrued interest payable and other liabilities	73,769	126,135
Accounts payable and accrued expenses	159,598	142,428
Deferred revenue/gains	321,764	357,193
Capitalized lease obligation	37,518	17,112
Deferred land leases payable	20,897	18,495
Dividend and distributions payable	37,839	28,398
Security deposits	46,253	46,367
Liabilities related to assets held for sale	136	61,988
Junior subordinate deferrable interest debentures held by trusts that issued trust preferred securities	100,000	100,000
Total liabilities	7,218,194	6,833,513
Commitments and contingencies
SLGOP partners' capital:
SL Green partners' capital (940 and 885 general partner common units and 90,310 and 84,897 limited partner common units outstanding at December 31, 2012 and 2011, respectively)	6,189,529	5,714,856
Limited partner interests in SLGOP (2,760 and 2,765 limited partner common units outstanding at December 31, 2012 and 2011, respectively	71,524	114,497
Accumulated other comprehensive loss	(30,649)	(29,119)
Total SLGOP partners' capital	6,632,709	6,170,577
Noncontrolling interests in other partnerships	487,301	477,762
Total capital	7,120,010	6,648,339
Total liabilities and capital	14,387,754	13,483,852
Series H Preferred Units
Liabilities
Preferred units	2,000	2,000
Series G Preferred Units
Liabilities
Preferred units	47,550
Series C preferred units
SLGOP partners' capital:
Preferred units	180,340	274,022
Total capital	180,340	274,022
Series D preferred units
SLGOP partners' capital:
Preferred units		96,321
Total capital		96,321
Series I Preferred Units
SLGOP partners' capital:
Preferred units	221,965
Total capital	$ 221,965