Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 32,844	$ 80,509	$ 86,477
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization, including amortization of debt issuance costs	38,499	38,681	36,374
Straight-lining of rental income	5,924	4,297	2,347
Stock-based compensation expense	394	394	450
Change in fair value of marketable securities (see Note 5)	11,990	0	0
Change in operating assets and liabilities:
Tenant and other receivables, net	(1,382)	363	958
Other assets	(1,197)	(2,627)	(9,894)
Amounts due to Vornado	(1,907)	1,626	(1,913)
Accounts payable and accrued expenses	(11,760)	211	16,049
Other liabilities	133	(28)	(28)
Net cash provided by operating activities	73,538	123,426	130,820
CASH FLOWS FROM INVESTING ACTIVITIES
Construction in progress and real estate additions	(3,966)	(3,434)	(15,506)
Rego Park II loan participation	0	(200,000)	0
Repayment of Rego Park II loan participation	2,829	1,463	0
Net cash used in investing activities	(1,137)	(201,971)	(15,506)
CASH FLOWS FROM FINANCING ACTIVITIES
Debt repayments	(160,142)	(303,707)	(3,440)
Proceeds from borrowing	78,246	500,000	0
Dividends paid	(92,100)	(86,961)	(81,822)
Debt issuance costs	(2,189)	(12,186)	(30)
Net cash (used in) provided by financing activities	(176,185)	97,146	(85,292)
Net (decrease) increase in cash and cash equivalents and restricted cash	(103,784)	18,601	30,022
Cash and cash equivalents and restricted cash at beginning of year	393,279	374,678	344,656
Cash and cash equivalents and restricted cash at end of year	289,495	393,279	374,678
RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH
Cash and cash equivalents at beginning of year	307,536	288,926	259,349
Restricted cash at beginning of year	85,743	85,752	85,307
Cash and cash equivalents and restricted cash at beginning of year	393,279	374,678	344,656
Cash and cash equivalents at end of year	283,056	307,536	288,926
Restricted cash at end of year	6,439	85,743	85,752
Cash and cash equivalents and restricted cash at end of year	289,495	393,279	374,678
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash payments for interest	38,231	26,994	19,517
NON-CASH TRANSACTIONS
Write-off of fully amortized and/or depreciated assets	16,090	4,265	1,691
Liability for real estate additions, including $125, $21, and $54 due to Vornado in 2018, 2017 and 2016, respectively	$ 631	$ 705	$ 322