Stock-based Compensation (Schedule of AO LTIP Units & Share Based Payment Award Stock Options Valuation Assumptions) (Details)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Vornado stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	35.00%
Expected volatility, maximum	36.00%
Expected volatility		35.00%
Expected life (years)	5 years	5 years
Risk free interest rate		2.50%
Risk free interest rate, minimum	0.57%
Risk free interest rate, maximum	1.76%
Expected dividend yield (percentage)		2.90%
Performance Conditioned AO LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility		35.00%
Expected life (years)		8 years
Risk free interest rate		2.76%
Expected dividend yield (percentage)		3.10%
AO LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	35.00%
Expected volatility, maximum	36.00%
Expected volatility		35.00%
Expected life (years)	5 years	5 years
Risk free interest rate		2.50%
Risk free interest rate, minimum	0.57%
Risk free interest rate, maximum	1.76%
Expected dividend yield (percentage)		2.90%
Minimum \| Vornado stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield (percentage)	3.20%
Minimum \| AO LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield (percentage)	3.20%
Maximum \| Vornado stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield (percentage)	3.40%
Maximum \| AO LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield (percentage)	3.40%

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

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The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

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- Definition

The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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