Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Commercial real estate properties, at cost:
Land and land interests	$ 2,937,866	$ 2,684,626
Building and improvements	7,438,364	7,147,527
Building leasehold and improvements	1,331,190	1,302,790
Property under capital lease	12,208	12,208
Total commercial real estate properties, at cost	11,719,628	11,147,151
Less: accumulated depreciation	(1,339,324)	(1,136,603)
Total commercial real estate properties, net	10,380,304	10,010,548
Assets held for sale	91,574	76,562
Cash and cash equivalents	162,363	138,192
Restricted cash	143,058	86,584
Investment in marketable securities	21,549	25,323
Tenant and other receivables, net of allowance of $21,575 and $16,772 in 2012 and 2011, respectively	35,315	32,107
Related party receivables		4,001
Deferred rents receivable, net of allowance of $30,076 and $29,156 in 2012 and 2011, respectively	330,349	281,974
Debt and preferred equity investments, net of discount of $13,207 and $24,996 and allowance of $7,000 and $50,175 in 2012 and 2011, respectively	1,071,641	985,942
Investments in unconsolidated joint ventures	1,020,790	893,933
Deferred costs, net	253,137	210,786
Other assets	774,859	737,900
Total assets	14,284,939	13,483,852
Liabilities
Mortgages and other loans payable	4,849,233	4,314,741
Revolving credit facility	200,000	350,000
Senior unsecured notes	1,176,252	1,270,656
Accrued interest payable and other liabilities	100,528	126,135
Accounts payable and accrued expenses	147,452	142,428
Deferred revenue/gains	360,752	357,193
Capitalized lease obligation	17,167	17,112
Deferred land leases payable	18,833	18,495
Dividend and distributions payable	29,154	28,398
Security deposits	47,698	46,367
Liabilities related to assets held for sale	63,202	61,988
Junior subordinate deferrable interest debentures held by trusts that issued trust preferred securities	100,000	100,000
Total liabilities	7,110,271	6,833,513
Commitments and contingencies
Noncontrolling interests in operating partnership	265,093	195,030
SL Green stockholders' equity:
Common stock, $0.01 par value 160,000 shares authorized and 93,970 and 89,210 issued and outstanding at September 30, 2012 and December 31, 2011, respectively (including 3,607 and 3,427 shares at September 30, 2012 and December 31, 2011, held in Treasury, respectively)	940	892
Additional paid-in-capital	4,589,423	4,236,959
Treasury stock at cost	(319,905)	(308,708)
Accumulated other comprehensive loss	(29,281)	(28,445)
Retained earnings	1,728,150	1,704,506
Total SL Green stockholders' equity	6,371,912	5,975,547
Noncontrolling interests in other partnerships	488,113	477,762
Total equity	6,860,025	6,453,309
Total liabilities and equity	14,284,939	13,483,852
Series C Preferred Stock
SL Green stockholders' equity:
Preferred stock	180,340	274,022
Total equity	180,340	274,022
Series D Preferred Stock
SL Green stockholders' equity:
Preferred stock		96,321
Total equity		96,321
Series H Preferred Units
Liabilities
Preferred Units	2,000	2,000
Series G Preferred Units
Liabilities
Preferred Units	47,550
Series I Preferred Stock
SL Green stockholders' equity:
Preferred stock	222,245
Total equity	$ 222,245