Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
REVENUES
Rental revenues	$ 199,142	$ 226,350	$ 232,825
EXPENSES
Operating, including fees to Vornado of $5,429, $5,386 and $4,700, respectively	(88,403)	(89,738)	(93,775)
Depreciation and amortization	(32,357)	(31,351)	(33,089)
General and administrative, including management fees to Vornado of $2,380	(6,307)	(5,772)	(5,343)
Total expenses	(127,067)	(126,861)	(132,207)
Interest and other income, net	2,667	8,244	12,546
Interest and debt expense	(24,204)	(38,901)	(44,533)
Change in fair value of marketable securities (see Note 6)	(8,599)	(8,757)	(11,990)
Income from continuing operations	41,939	60,075	56,641
Loss from discontinued operations (see Note 7)	0	0	(23,797)
Net income	$ 41,939	$ 60,075	$ 32,844
Income per common share - basic and diluted:
Income from continuing operations - basic and diluted (in usd per share)	$ 8.19	$ 11.74	$ 11.07
Loss from discontinued operations - basic and diluted (in usd per share)	0	0	(4.65)
Net income per common share - basic and diluted (in usd per share)	$ 8.19	$ 11.74	$ 6.42
Weighted average shares outstanding - basic and diluted (in shares)	5,120,922	5,118,198	5,116,838