Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Commercial real estate properties, at cost:
Land and land interests	$ 2,886,099	$ 2,886,099
Building and improvements	7,452,347	7,389,766
Building leasehold and improvements	1,346,481	1,346,748
Properties under capital lease	47,179	40,340
Total commercial real estate properties, at cost	11,732,106	11,662,953
Less: accumulated depreciation	(1,461,775)	(1,393,323)
Total commercial real estate properties, net	10,270,331	10,269,630
Assets held for sale		4,901
Cash and cash equivalents	220,104	189,984
Restricted cash	130,233	136,071
Investment in marketable securities	22,994	21,429
Tenant and other receivables, net of allowance of $20,947 and $21,652 in 2013 and 2012, respectively	41,950	48,544
Related party receivables	11,169	7,531
Deferred rents receivable, net of allowance of $28,475 and $29,580 in 2013 and 2012, respectively	355,250	340,747
Debt and preferred equity investments, net of discount of $11,251 and $13,572 and allowance of $7,000 both in 2013 and 2012, respectively	1,443,834	1,357,203
Investments in unconsolidated joint ventures	1,073,130	1,032,243
Deferred costs, net	252,018	261,145
Other assets	722,952	718,326
Total assets	14,543,965	14,387,754
Liabilities
Mortgages and other loans payable	4,815,485	4,615,464
Revolving credit facility	30,000	70,000
Term loan and senior unsecured notes	1,732,588	1,734,956
Accrued interest payable and other liabilities	73,666	73,769
Accounts payable and accrued expenses	143,812	159,598
Deferred revenue	322,317	321,764
Capitalized lease obligations	43,404	37,518
Deferred land leases payable	19,750	20,897
Dividend and distributions payable	37,737	37,839
Security deposits	49,803	46,253
Liabilities related to assets held for sale		136
Junior subordinate deferrable interest debentures held by trusts that issued trust preferred securities	100,000	100,000
Total liabilities	7,368,562	7,218,194
Commitments and contingencies
Noncontrolling interest in the Operating Partnership	220,174	212,907
SL Green stockholders' equity:
Common stock, $0.01 par value 160,000 shares authorized and 95,201 and 94,896 issued and outstanding at March 31, 2013 and December 31, 2012, respectively (including 3,646 and 3,646 shares held in Treasury at March 31, 2013 and December 31, 2012, respectively)	953	950
Additional paid-in-capital	4,697,528	4,667,900
Treasury stock at cost	(322,858)	(322,858)
Accumulated other comprehensive loss	(26,117)	(29,587)
Retained earnings	1,665,468	1,701,092
Total SL Green stockholders' equity	6,417,246	6,419,802
Noncontrolling interests in other partnerships	488,433	487,301
Total equity	6,905,679	6,907,103
Total liabilities and equity	14,543,965	14,387,754
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
SL Green stockholders' equity:
Preferred stock	180,340	180,340
Series I Preferred Stock
SL Green stockholders' equity:
Preferred stock	$ 221,932	$ 221,965