Commitments and Contingencies (Details)	6 Months Ended
	Jun. 30, 2017 USD ($)
Other Commitments
Guarantees and master leases	$ 774,000,000
Outstanding letters of credit	20,777,000
Commitment To Fund Additional Capital To Partially Owned Entities	52,000,000
Constuction commitments	543,000,000
Washington DC
Other Commitments
Real estate disposition transaction cost	47,000,000
General Liability
Insurance
Insurance limit per occurrence	300,000,000
Insurance limit per property	300,000,000
Terrorism Acts
Insurance
Insurance limit per occurrence	4,000,000,000
Annual aggregate insurance coverage	4,000,000,000
NBCR Acts
Insurance
Insurance limit per occurrence	2,000,000,000
Annual aggregate insurance coverage	$ 2,000,000,000
Insurance Coverage End Date	December 2020
Earthquake California Properties
Insurance
Insurance limit per occurrence	$ 180,000,000
Insurance maximum coverage limit in aggregate	$ 180,000,000
Vornado deductible, percentage of property value	5.00%
All Risk And Rental Value
Insurance
Insurance limit per occurrence	$ 2,000,000,000
PPIC | NBCR Acts
Insurance
Insurance deductible	$ 1,976,000
Insurance Deductible Percentage Of Balance Of Covered Loss	17.00%