Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 76,907	$ 67,925	$ 56,915
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization, including amortization of debt issuance costs	33,671	31,919	31,395
Straight-lining of rental income	(1,418)	(2,538)	(3,707)
Stock-based compensation expense	600	394	394
Reversal of income tax liability	0	(420)	(206)
Change in operating assets and liabilities:
Tenant and other receivables, net	(1,801)	712	(972)
Other assets	(4,777)	(4,334)	(472)
Amounts due to Vornado	2,228	(42,779)	(3,138)
Accounts payable and accrued expenses	822	(1,373)	(6,284)
Other liabilities	(31)	(19)	(42)
Net cash provided by operating activities	106,201	49,487	73,883
CASH FLOWS FROM INVESTING ACTIVITIES
Construction in progress and real estate additions	(50,121)	(61,964)	(7,671)
Proceeds from maturing (purchases of) short-term investments	24,998	(24,998)	0
Restricted cash	(705)	5,442	351
Net cash used in investing activities	(25,828)	(81,520)	(7,320)
CASH FLOWS FROM FINANCING ACTIVITIES
Debt repayments	(323,193)	(317,179)	(15,957)
Proceeds from borrowing	350,000	300,000	0
Dividends paid	(71,571)	(66,436)	(56,197)
Debt issuance costs	(4,075)	(4,255)	(87)
Net cash used in financing activities	(48,839)	(87,870)	(72,241)
Net increase (decrease) in cash and cash equivalents	31,534	(119,903)	(5,678)
Cash and cash equivalents at beginning of year	227,815	347,718	353,396
Cash and cash equivalents at end of year	259,349	227,815	347,718
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash payments for interest, excluding capitalized interest of $1,486 and $603 in 2015 and 2014, respectively	22,354	30,656	42,121
NON-CASH TRANSACTIONS
Liability for real estate additions, including $5,795 and $3,394 due to Vornado in 2015 and 2014, respectively	10,139	13,529	1,084
Write-off of fully amortized and/or depreciated assets	$ 20,786	$ 10,626	$ 0