Investments in Partially Owned Entities (Independance Plaza and 650 Madison Avenue) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			0 Months Ended			0 Months Ended								0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jun. 07, 2013 Independence Plaza [Member]	Dec. 21, 2012 Independence Plaza [Member] Residential	Dec. 31, 2012 Independence Plaza [Member]	Jun. 07, 2013 Independence Plaza [Member] Vornado Realty Trust [Member]	Jun. 07, 2013 Independence Plaza [Member] Five Year Interest Only Loan [Member]	Dec. 31, 2012 Independence Plaza [Member] Land [Member]	Dec. 31, 2012 Independence Plaza [Member] Building Improvements [Member]	Dec. 31, 2012 Independence Plaza [Member] Acquired above-market leases (included in identified intangible assets) [Member]	Dec. 31, 2012 Independence Plaza [Member] Acquired in-place leases (included in identified intangible assets) [Member]	Dec. 31, 2012 Independence Plaza [Member] Other Assets [Member]	Dec. 31, 2012 Independence Plaza [Member] Acquired below-market leases (included in deferred revenue) [Member]	Sep. 30, 2013 Madison Avenue 650 [Member] Story sqft	Sep. 30, 2013 Madison Avenue 650 [Member] Office Space [Member] sqft	Sep. 30, 2013 Madison Avenue 650 [Member] Retails Space [Member] sqft
Business Acquisition [Line Items]
Variable Interest Entity Ownership Percentage					58.75%
Number of Units in Real Estate Property (in number of residential units)/ (in number of rooms)					1,328
Purchase Price Allocation, Land					$ 309,848
Purchase Price Allocation, Buildings					527,578
Purchase Price Allocation, Assets Acquired						844,800			602,662	252,844	13,115	67,879	7,374	(99,074)
Equity method ownership percentage															20.10%
Number Of Story In Office Tower															27
Square Footage Of Real Estate Property															594,000	523,000	71,000
Cost Of Acquired Entity Purchase Price															1,295,000
Debt Instruments [Abstract]
Mortgages payable	8,331,993	8,599,222		323,000				550,000							800,000
Debt Term				5 years											7 years
Interest Rate, End of Period (in percentage)								3.48%							4.39%
Net proceeds after repaying the existing loan and closing costs				219,000			137,000
Equity Method Investment Ownership Percentage Sold				8.65%
Sale of economic interest, value				41,000
Vornado's economic interest in subsidiary after sale (in percentage)				50.10%
Condensed Financial Information For Equity Method Investments [Abstract]
Assets	21,773,000	122,692,000
Liabilities	17,982,000	117,064,000
Noncontrolling interests	96,000	88,000
Equity	3,695,000	5,540,000
Total revenue	14,092,000	15,119,000	15,321,000
Net (loss) income attributable to investee	$ (368,000)	$ 1,091,000	$ 199,000