Stock-based Compensation (Summary of Unrecognized Compensation Expense) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 34,103
Weighted-Average Remaining Contractual Term	1 year 8 months 12 days
OP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 25,661
Weighted-Average Remaining Contractual Term	1 year 7 months 6 days
OPPs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 3,882
Weighted-Average Remaining Contractual Term	2 years 1 month 6 days
AO LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 2,286
Weighted-Average Remaining Contractual Term	1 year 6 months
Vornado restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 974
Weighted-Average Remaining Contractual Term	1 year 8 months 12 days
Vornado stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 987
Weighted-Average Remaining Contractual Term	1 year 8 months 12 days
Performance Conditioned AO LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 313
Weighted-Average Remaining Contractual Term	1 year 3 months 18 days