Commitments and Contingencies (Details)	9 Months Ended
	Sep. 30, 2019 USD ($)
Other Commitments
Guarantees and master leases	$ 978,000,000
Outstanding letters of credit	15,880,000
Commitment to fund additional capital to partially owned entities	15,400,000
Construction commitment	746,000,000
General Liability
Insurance
Insurance limit per property	300,000,000
Insurance limit per occurrence	300,000,000
All Risk And Rental Value
Insurance
Insurance limit per occurrence	2,000,000,000.0
Earthquake California Properties
Insurance
Insurance limit per occurrence	350,000,000
Insurance maximum coverage limit in aggregate	$ 350,000,000
Vornado deductible, percentage of property value	5.00%
Non-Certified Acts of Terrorism
Insurance
Insurance maximum coverage limit in aggregate	$ 760,000,000
Terrorism Acts
Insurance
Insurance limit per occurrence	4,000,000,000
Insurance maximum coverage limit in aggregate	4,000,000,000.0
NBCR Acts
Insurance
Insurance limit per occurrence	2,000,000,000
Insurance maximum coverage limit in aggregate	2,000,000,000.0
PPIC | NBCR Acts
Insurance
Insurance deductible	$ 1,456,071
Insurance deductible percentage of balance of covered loss	19.00%
Farley Office and Retail Building
Other Commitments
Equity method ownership percentage	95.00%
Farley Office and Retail Building | General Liability
Insurance
Insurance limit per occurrence	$ 100,000,000
Farley Office and Retail Building | Non-Certified Acts of Terrorism
Insurance
Insurance limit per occurrence	1,000,000,000.0
Insurance maximum coverage limit in aggregate	1,000,000,000.0
Farley Office and Retail Building | Terrorism Acts
Insurance
Insurance limit per occurrence	1,000,000,000.0
Insurance maximum coverage limit in aggregate	1,000,000,000.0
Farley Office and Retail Building | Property and Development Activities
Insurance
Insurance limit per occurrence	2,800,000,000
Insurance maximum coverage limit in aggregate	$ 2,800,000,000.0
Joint Venture | Farley Office and Retail Building
Other Commitments
Equity method ownership percentage	95.00%