Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 41,939	$ 60,075	$ 32,844
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization, including amortization of debt issuance costs	35,121	36,515	38,499
Straight-lining of rents	21,102	2,413	5,924
Write-off of tenant receivables	4,122	0	0
Stock-based compensation expense	600	394	394
Change in fair value of marketable securities	8,599	8,757	11,990
Dividends received in stock	(214)	0	0
Change in operating assets and liabilities:
Tenant and other receivables, net	(6,146)	(2,017)	(1,382)
Other assets	(28,378)	21,553	(1,197)
Amounts due to Vornado	(402)	789	(1,907)
Accounts payable and accrued expenses	2,361	(1,800)	(11,760)
Other liabilities	(638)	(609)	133
Net cash provided by operating activities	78,066	126,070	73,538
CASH FLOWS FROM INVESTING ACTIVITIES
Construction in progress, real estate additions and other	(32,460)	(9,449)	(3,966)
Repayment of Rego Park II loan participation	0	0	2,829
Net cash used in investing activities	(32,460)	(9,449)	(1,137)
CASH FLOWS FROM FINANCING ACTIVITIES
Dividends paid	(92,168)	(92,124)	(92,100)
Debt issuance costs	(7,246)	(15)	(2,189)
Debt repayments	(50,000)	0	(160,142)
Proceeds from borrowings	239,708	0	78,246
Net cash provided by (used in) financing activities	90,294	(92,139)	(176,185)
Net increase (decrease) in cash and cash equivalents and restricted cash	135,900	24,482	(103,784)
Cash and cash equivalents and restricted cash at beginning of year	313,977	289,495	393,279
Cash and cash equivalents and restricted cash at end of year	449,877	313,977	289,495
RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH
Cash and cash equivalents at beginning of year	298,063	283,056	307,536
Restricted cash at beginning of year	15,914	6,439	85,743
Cash and cash equivalents and restricted cash at beginning of year	313,977	289,495	393,279
Cash and cash equivalents at end of year	428,710	298,063	283,056
Restricted cash at end of year	21,167	15,914	6,439
Cash and cash equivalents and restricted cash at end of year	449,877	313,977	289,495
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash payments for interest	22,476	34,669	38,231
NON-CASH TRANSACTIONS
Liability for real estate additions, including $489, $18 and $125 for development fees due to Vornado in 2020, 2019 and 2018, respectively	4,955	3,191	631
Write-off of fully amortized and/or depreciated assets	876	0	16,090
Reclassification of prepaid real estate taxes to construction in progress for property in redevelopment	0	1,466	0
Lease liability arising from the recognition of right-of-use asset	0	5,428	0
Derecognition of Rego Park II loan participation asset	$ 0	$ 0	$ 195,708