Real Estate Fund Investments (Narrative) (Details) $ in Thousands		9 Months Ended
	Dec. 31, 2019 USD ($) investment	Sep. 30, 2020 USD ($) investment	Jun. 09, 2020 USD ($)
Investment Holdings
Aggregate fair value of Real Estate Fund investments (in US Dollars)	$ 222,649	$ 3,739
Vornado Capital Partners Real Estate Fund
Investment Holdings
Equity method ownership percentage		25.00%
Investment fund period expiration date		2013-07
Investment fund, extension of term		2023-02
Term of the Fund, years		8 years
Investment period for commitments of the Fund, years		3 years
Crowne Plaza Times Square Hotel Joint Venture
Investment Holdings
Default amount			$ 274,355
Debt instrument, interest rate, stated percentage (percent)		3.90%
Debt instrument, default interest, percentage		3.00%
Real estate fund investments
Investment Holdings
Number of investments held by fund (investment) | investment	4	4
Aggregate fair value of Real Estate Fund investments (in US Dollars)	$ 222,649	$ 3,739
Fair value below cost		338,327
Unfunded commitments of fund		$ 28,692
Joint Venture | Crowne Plaza Times Square Hotel Joint Venture
Investment Holdings
Equity method ownership percentage		57.10%
Crowne Plaza Time Square Hotel | Joint Venture | Crowne Plaza Times Square Hotel Joint Venture
Investment Holdings
Ownership percentage by noncontrolling owners		24.70%
Vornado Realty Trust | Real estate fund investments
Investment Holdings
Unfunded commitments of fund		$ 9,140
LIBOR | Crowne Plaza Times Square Hotel Joint Venture
Investment Holdings
Spread over LIBOR (percent)		3.69%