Stock-based Compensation (Out Performance Plans Narrative) (Details)		3 Months Ended				12 Months Ended
	Mar. 15, 2018	Dec. 31, 2019 USD ($) shares	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) component	Dec. 31, 2017 USD ($)	May 16, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated cost					$ 16,211,000
Share-based compensation expense		$ (2,578,000)	$ (2,578,000)	$ (2,578,000)						$ 53,908,000	$ 31,722,000	$ 32,829,000
Full Value Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares		5,207,000								5,207,000
OPPs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense										$ 1,944,000	10,689,000	10,723,000
Out Performance Plan
Share-based compensation expense											8,040,000	$ 7,558,000
Out Performance Plan 2018
Out Performance Plan
Out of performance plan notional amount		$ 35,000,000								$ 35,000,000	$ 35,000,000
Number of components of out performance plan | component											2
Amount of basis points by which Vornado underperforms the index, total											6.00%
Amount of basis points by which Vornado underperforms the index											2.00%
Percentage of notional amount granted										78.20%
Grant-date fair value		10,300,000								$ 10,300,000
OPP Units Earned										To be determined in 2021
Out Performance Plan 2017
Out Performance Plan
Out of performance plan notional amount		35,000,000								$ 35,000,000
Percentage of notional amount granted										86.60%
Grant-date fair value		10,800,000								$ 10,800,000
OPP Units Earned										Not earned
Out Performance Plan 2016
Out Performance Plan
Out of performance plan notional amount		40,000,000								$ 40,000,000
Percentage of notional amount granted										86.70%
Grant-date fair value		11,800,000								$ 11,800,000
OPP Units Earned										Not earned
Award Amortization Period										5 years
Absolute | Out Performance Plan 2018
Out Performance Plan
Duration of performance measurement period	3 years										3 years
Required shareholder return three year											21.00%
Relative | Out Performance Plan 2018
Out Performance Plan
Required shareholder return under relative component											3.00%
Percentage awards will be reduced if total shareholder return is zero or negative											0.00%
Relative | Out Performance Plan 2018 | Maximum
Out Performance Plan
Percentage awards will be reduced if total shareholder return is zero or negative											50.00%
SNL US Office REIT Index | Relative | Out Performance Plan 2018
Out Performance Plan
Required shareholder return per year											70.00%
SNL US Retail Index | Relative | Out Performance Plan 2018
Out Performance Plan
Required shareholder return per year											30.00%
2019 Omnibus Share Plan | Full Value Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares													5,500,000
2019 Omnibus Share Plan | Not Full Value Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares													11,000,000
Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense									$ (8,477,000)
Forecast | 2019 Omnibus Share Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense						$ 2,655,000	$ 7,718,000	$ 9,603,000	$ 9,603,000
Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense										$ 8,143,000
Out Performance Plan
Grant-date fair value		25,500,000								25,500,000
Executive Officer | 2019 Omnibus Share Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense										2,304,000
Out Performance Plan
Grant-date fair value		$ 15,000,000								$ 15,000,000
Share-based Payment Arrangement, Tranche One | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage										20.00%
Share-based Payment Arrangement, Tranche Two | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage										40.00%
Share-based Payment Arrangement, Tranche Three | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage										40.00%