Commitments and Contingencies (Details) - USD ($)	9 Months Ended
	Sep. 30, 2015	Jan. 01, 2016
Loss Contingencies [Line Items]
Guarantees and master leases	$ 430,000,000
Outstanding letters of credit	40,647,000
Commitment To Fund Additional Capital To Partially Owned Entities	76,000,000
NBCR Losses [Member]
Loss Contingencies [Line Items]
Insurance limit per occurrence	2,000,000,000
Insurance Limit Aggregate Value	$ 2,000,000,000
Federal government deductible, percentage of balance of a covered loss	85.00%	84.00%
Earthquake California Properties [Member]
Loss Contingencies [Line Items]
Insurance limit per occurrence	$ 180,000,000
Vornado deductible, percentage of property value	5.00%
Vornado deductible, annual aggregate	$ 180,000,000
All Risk And Rental Value [Member]
Loss Contingencies [Line Items]
Insurance limit per occurrence	2,000,000,000
General Liability [Member]
Loss Contingencies [Line Items]
Insurance limit per occurrence	300,000,000
Terrorism Acts [Member]
Loss Contingencies [Line Items]
Insurance limit per occurrence	4,000,000,000
Insurance Limit Aggregate Value	$ 4,000,000,000
Insurance Coverage End Date	December 2020
PPIC [Member] | NBCR Losses [Member]
Loss Contingencies [Line Items]
Insurance deductible	$ 2,480,000
Insurance Deductible Percentage Of Balance Of Covered Loss	15.00%	16.00%