Commitments and Contingencies (Details) (USD $)						12 Months Ended							0 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 NBCR Losses [Member]	Dec. 31, 2012 Earthquake California Properties [Member]	Dec. 31, 2012 All Risk And Rental Value [Member]	Dec. 31, 2012 General Liability [Member]	Dec. 31, 2012 PPIC [Member] NBCR Losses [Member]	Dec. 31, 2012 Central Park South 220 [Member]	Dec. 31, 2012 Stop & Shop [Member]	Jan. 12, 2012 Stop & Shop [Member]	Dec. 31, 2011 Stop & Shop [Member]	Dec. 16, 2011 Stop & Shop [Member]	Feb. 28, 2011 Stop & Shop [Member]	Feb. 06, 2013 Stop & Shop [Member] Subsequent Event [Member]	Dec. 31, 2012 Cleveland Medical Mart & Convention Center [Member]
Federal government deductible, percentage of balance of a covered loss		85.00%
Vornado deductible, annual aggregate			$ 180,000,000
Insurance limit per occurrence		2,000,000,000	180,000,000	2,000,000,000	300,000,000
Guarantees and master leases	310,249,000
Vornado deductible, percentage of property value			5.00%
Outstanding letters of credit	22,807,000
Commitment to fund additional capital to partially owned entities							163,130,000
Stop & Shop complaint regarding rent allocated to East Brunswick, Jersey City, Middletown, Union, and Woodbridge leases								6,000,000		5,000,000
Insurance deductible						3,200,000
Insurance Deductible Percentage Of Balance Of Covered Loss						15.00%
Commitments to Fund Improvements														11,500,000
Commitment Funded During Period														1,100,000
Proceed pursuant to a settlement agreement													124,000,000
Gain Loss On Contract Termination													59,000,000
Accrued Annual Rent Payable By Stop And Shop As Per Court Judgement											56,597,000	37,422,000
Accounts Receivable, Gross								47,900,000
Stop & Shop recovery action of annual rent commenced by Vornado									$ 2,500,000