Commitments and Contingencies (Details) (USD $)	9 Months Ended
	Sep. 30, 2011
Guarantees and master leases	$ 151,959,000
Outstanding letters of credit	22,085,000
Commitment to fund additional capital to partially owned entities	264,000,000
PPIC [Member] | NBCR Losses [Member]
Insurance deductible	3,200,000
Insurance Deductible Percentage Of Balance Of Covered Loss	15.00%
Central Park South 220 [Member]
Commitment to fund Central Park South project, low end of range	400,000,000
Commitment to fund Central Park South project, high end of range	425,000,000
Stop & Shop [Member]
Stop & Shop complaint regarding annual rent collected pursuant to Master Agreement and Guaranty	5,000,000
Stop & Shop complaint regarding rent allocated to East Brunswick, Jersey City, Middletown, Union, and Woodbridge leases	5,000,000
Accounts Receivable, Gross	40,733,000
Allowance for Doubtful Accounts Receivable	23,105,000
Loss Contingency, Opinion of Counsel	We believe, after consultation with counsel, that the maximum reasonably possible loss is up to the total amount of the receivable of $40,733,000.
NBCR Losses [Member]
Federal government deductible, percentage of balance of a covered loss	85.00%
Insurance limit per occurrence	2,000,000,000
Earthquake California Properties [Member]
Vornado deductible, annual aggregate	180,000,000
Insurance limit per occurrence	180,000,000
Vornado deductible, percentage of property value	5.00%
All Risk And Rental Value [Member]
Insurance limit per occurrence	2,000,000,000
General Liability [Member]
Insurance limit per occurrence	$ 300,000,000